For Week 3's forum, read the case "China Noah Corporation" that...
For Week 3's forum, read the case "China Noah Corporation" that...
For Week 3's forum, read the case "China Noah Corporation" that begins on p. 301-307 in Chapter 10 and answer the following questions:
- What would be your outlook on the future direction of the Indonesian rupiah and the Chinese renminbi?
- Should this influence the hedging approach used by Noah?
- Which of the hedging choices would you recommend?
- Are there any operational strategies that Noah could take to help manage the risks? Why or why not?
- with Reference
Answer & Explanation
- The outlook for the Chinese yuan and the Indonesian rupiah is uncertain, but both currencies have the potential to appreciate over the long term if the economies of their respective countries are able to bring down their current account deficits, improve their fiscal balances, and enjoy robust economic development. The state of the economy in the rest of the world will also play a significant role in determining the path that each currency will take in the future.
- Noah has significant exposure to both of these currencies due to its business activities in Indonesia and China. To protect itself against potential losses, it should adopt a more prudent strategy that involves forward contracts and options. It should also keep a close eye on the economic situations in both Indonesia and China to predict any potential shifts in the value of the rupiah and the yuan.
- Noah should consider a combination of forward contracts, options, and currency swaps as its hedging strategy, as well as monitoring economic conditions in both Indonesia and China to anticipate potential changes in the value of the rupiah and renminbi.
- Noah should consider engaging in hedging strategies such as forward contracts, options, and currency swaps, implementing a foreign exchange risk management policy, diversifying its business operations, and monitoring economic conditions in both countries to manage currency fluctuations.
- There is a great deal of unpredictability about the route that the Chinese yuan and the Indonesian rupiah will take in the years to come. Both the rupiah and the renminbi are expected to maintain their trend of being highly unstable in the near future. The rising value of the Chinese yuan can be attributed to the country's robust economic performance, in contrast to the weakening value of the Indonesian rupiah, which can be attributed to the country's widening current account deficit.
- On the other hand, over the longer run, the value of both currencies may increase. If Indonesia is successful in narrowing its current account deficit and improving its fiscal condition, the Indonesian rupiah may experience some appreciation in value. If China's economy maintains its robust growth rate and the country's currency is permitted to appreciate further in value, the value of the Chinese renminbi (CNY) could rise.
- It is also essential to keep in mind that the outlook for both currencies is dependent on the state of the economy in the rest of the world. Both currencies have the potential to profit from an increase in demand for their respective exports if the current robust economic circumstances throughout the world continue. On the other side, if the state of the economy throughout the world deteriorates, then the value of both currencies may come under pressure to decline.
- The outlook for the Chinese yuan and the Indonesian rupiah is dubious in general. Both currencies might continue their erratic behavior over the next few months. On the other hand, both currencies have the potential to appreciate over the long term if the economies of their respective countries are able to bring down their current account deficits, improve their fiscal balances, and enjoy robust economic development. The state of the economy in the rest of the world will also play a significant role in determining the path that each currency will take in the future.
- Without a doubt, the prognosis for the Indonesian rupiah and the Chinese yuan ought to have an impact on the method of hedging that Noah employs. As the case illustrates, Noah has significant exposure to both of these currencies due to the fact that it conducts business activities in Indonesia as well as China. Noah is going to need to implement a hedging plan so that it can safeguard itself against the possibility of incurring losses due to shifts in currency values.
- In light of the fact that the future value of both currencies is hard to predict, Noah ought to think about adopting a more prudent strategy for hedging. This might involve a combination of forward contracts and options, both of which would enable Noah to lock in exchange rates and protect itself from losses resulting from currency volatility. Noah could also think about acquiring options, since they would give the company the flexibility to capitalize on any future appreciation in either the rupiah or the renminbi.
- Noah ought to also think about keeping a careful eye on the economic situations in both Indonesia and China in order to predict any potential shifts in the value of the rupiah and the yuan. Because of this, Noah might be able to change its hedging strategy in a way that is more suitable to ensuring that it is appropriately covered against currency swings.
- In general, the prognosis for the Indonesian rupiah and the Chinese yuan ought to have some bearing on the kind of hedging that Noah employs. In order to safeguard itself against the possibility of financial losses brought on by shifts in currency values, Noah should give serious consideration to adopting a hedging strategy that is more prudent and incorporates a mix of forward contracts and options. Also, Noah needs to keep a close eye on the state of the economies in both nations in order to adapt its hedging strategy appropriately.
- Given the uncertain outlook for the Indonesian rupiah and the Chinese renminbi, I would recommend Noah consider a combination of forward contracts and options as its hedging strategy. A forward contract would allow Noah to lock in exchange rates and protect itself from losses due to currency fluctuations. At the same time, purchasing options would provide Noah with the flexibility to take advantage of any potential appreciation in the rupiah or renminbi. I would also recommend Noah consider engaging in currency swaps.
- Currency swaps allow Noah to exchange currencies between two countries without having to undertake a foreign exchange transaction. This could be beneficial for Noah, as it would enable it to take advantage of any potential appreciation in either the rupiah or the renminbi, while also protecting itself from losses due to currency fluctuations. Finally, I would recommend Noah consider monitoring economic conditions in both Indonesia and China closely in order to anticipate any potential changes in the value of the rupiah and renminbi.
- This could help Noah adjust its hedging strategy accordingly in order to ensure it is adequately protected from currency fluctuations. Overall, I would recommend Noah consider a combination of forward contracts, options, and currency swaps as its hedging strategy. Additionally, Noah should monitor economic conditions in both countries in order to adjust its hedging strategy accordingly.
- Yes, there are a number of operational strategies that Noah could take to help manage the risks associated with currency fluctuations. First, Noah should consider engaging in hedging strategies such as forward contracts, options, and currency swaps. These strategies would allow Noah to lock in exchange rates and protect itself from losses due to currency fluctuations. Second, Noah should consider implementing a foreign exchange risk management policy. This policy would outline the company's objectives and strategies for managing foreign exchange risk. It would also provide guidance on how to monitor and adjust the company's hedging strategies in order to ensure that they are meeting the company's risk management objectives. Third, Noah should consider diversifying its business operations. T
- his would allow Noah to spread its risk across multiple currencies and potentially reduce its exposure to any one particular currency. Finally, Noah should consider monitoring economic conditions in both Indonesia and China closely in order to anticipate any potential changes in the value of the rupiah and renminbi. This could help Noah adjust its hedging strategy accordingly in order to ensure it is adequately protected from currency fluctuations. Overall, there are a number of operational strategies that Noah could take to help manage the risks associated with currency fluctuations. These strategies include engaging in hedging strategies, implementing a foreign exchange risk management policy, diversifying its business operations, and monitoring economic conditions in both countries.
- Vaka, M., Walvekar, R., Rasheed, A. K., & Khalid, M. (2020). A review on Malaysia's solar energy pathway towards carbon-neutral Malaysia beyond Covid'19 pandemic. Journal of cleaner production , 273 , 122834.
- Biden Jr, J. R. (2020). Why American Must Lead Again: Recusing US Foreign Policy after Trump. Foreign Aff. , 99 , 64.
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Noah Wealth Management
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- Wealth Economics, Econometrics and Finance 100%
- Management Economics, Econometrics and Finance 50%
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T1 - Noah Wealth Management
AU - Velamuri, S. Ramakrishna
AU - Ding, Yuan
AU - Zhu, Jianhua
PY - 2012/1/1
Y1 - 2012/1/1
N2 - Noah Wealth Management was founded by Ms Wang Jingbo, a lady in her mid 30s with a team of less than 20 members in 2005. Exploiting market opportunities offered by a lack of good wealth management products and services, Noah grew rapidly from one branch office in 2005 to 59 branch offices in 2011, reaching a staff size of 1,031. Noah listed its shares on the New York Stock Exchange in November 2010. In 2011, Noah was ranked No. 38 among the 100 Top Potential Enterprises in China. Nonetheless, Noah faced several problems of internal management during the course of its fast expansion. In the first quarter financial report of 2012, Noah suffered a 52.6 percent decrease in net income over the corresponding period in 2011. Faced with a rapidly declining share price, Noah announced on May 22, 2012 a US $30 million share repurchase program. Expected learning outcomes The case supports a basic lesson on the entrepreneurial cycle, including assessing a business opportunity, resource mobilization, identifying a business model, growth of the venture, listing on the stock market, and subsequent growth challenges. Students can learn about some of the typical dilemmas faced by founders of entrepreneurial ventures, including how to maintain the corporate culture while growing fast and how to prevent members of the founding team from becoming bottlenecks to the development of the organization. The case can also provide management students with an overview of China's wealth management industry.
AB - Noah Wealth Management was founded by Ms Wang Jingbo, a lady in her mid 30s with a team of less than 20 members in 2005. Exploiting market opportunities offered by a lack of good wealth management products and services, Noah grew rapidly from one branch office in 2005 to 59 branch offices in 2011, reaching a staff size of 1,031. Noah listed its shares on the New York Stock Exchange in November 2010. In 2011, Noah was ranked No. 38 among the 100 Top Potential Enterprises in China. Nonetheless, Noah faced several problems of internal management during the course of its fast expansion. In the first quarter financial report of 2012, Noah suffered a 52.6 percent decrease in net income over the corresponding period in 2011. Faced with a rapidly declining share price, Noah announced on May 22, 2012 a US $30 million share repurchase program. Expected learning outcomes The case supports a basic lesson on the entrepreneurial cycle, including assessing a business opportunity, resource mobilization, identifying a business model, growth of the venture, listing on the stock market, and subsequent growth challenges. Students can learn about some of the typical dilemmas faced by founders of entrepreneurial ventures, including how to maintain the corporate culture while growing fast and how to prevent members of the founding team from becoming bottlenecks to the development of the organization. The case can also provide management students with an overview of China's wealth management industry.
KW - Emerging markets
KW - Entrepreneurial finance
KW - Entrepreneurship
KW - Financial services
U2 - 10.1108/20450621211312929
DO - 10.1108/20450621211312929
M3 - Case Studies
McDonald’s and China Noah Corporation’s Finance
China noah corporation.
The reason why companies hedge against foreign currency risks is to protect themselves against loss of business value. China Noah has a different form of foreign currency exposure due to transactions involved when dealing with international customers and suppliers. This exposure arises when China Noah has entered into international financial obligations that are exposed to currency rate fluctuation. Moffett (2015) noted that companies are exposed to substantial foreign currency risk as they endeavor to boost sales revenues or obtain raw materials (p. 34). The foreign exchange risk is critical because it can reduce business value. Therefore, McDonald must hedge to protect against loss of business value.
When China Noah applies the forecast spot-rate model, profitability declines significantly due to the foreign exchange losses. However, when the company applies a forward rate quote, sales revenues increases significantly. If the company uses fix rate baseline assumption, the result will be unclear since the exchange rate cannot be predicted with precision over the next five years.
The schedule of the foreign currency exposure will be based on the exchange rate at the time of purchasing the raw material. Since China Noah intends to buy raw materials from Indonesia today, the foreign currency exposure will be determined by the exchange rate today unless payment is discounted on monthly bases (David, Arthur & Michael, 2015, p. 46).
The outlook of both currencies is imperative when making a decision on the best hedging strategy to be implemented since it determines foreign exchange losses. For instance, if the Indonesian Rupiah is expected to appreciate over the next five years, China Noah must hedge its business against foreign exchange transactions exposure.
The best hedging model is spot rate forecast since it minimizes exposure against rising Indonesian Rupiah over the next five years.
The three major exposures facing British McDonald subsidiary can be successfully hedged using cross-currency swap. These risks are caused by the fact that the equity capital is highly dependent on the value of a pound. Secondly, the subsidiary is exposed to Intra Company 4 year L125 million debts at an interest rate of 5.3%. McDonald has effectively been able to alter the denomination of cash flow in debts that affect interest rate structure. McDonald can be able to hedge against these foreign exchange exposures by swapping the fixed rate to decrease interest rate payable whenever they expect floatation rate to decrease.
McDonald subsidiary in the UK has been able to hedge its business against foreign exchange risk by employing a seven-year swap strategy. This model allows the company to hedge against foreign exchange fluctuations when the company receives payment in pounds. Moreover, the model allows the company to settle its obligations in pounds without incurring foreign exchange losses while they receive principal payments at the end of the swap agreement. McDonald lock-in its regular payments in dollars against any rising costs as a result of appreciating pound.
The most critical decision is for a parent company to determine whether the inter-company loan should be permanent or not. When the parent company decided the loan is permanent, foreign gains and losses are absorbed by the parent company and are reflected in the profit and loss account. Therefore, Anka should pay attention to OCI because it has a direct impact on shareholders equity.
David, K., Arthur, I., & Michael, H. (2015). Fundamentals of Multinational Finance . City: Pearson Education Limited.
Moffett, M. (2015). Fundamentals of Multinational Finance . City: Pearson Education Limited.
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Is China’s Economic Dominance at an Inflection Point?
- Allen J. Morrison
- J. Stewart Black
Six reasons why its position at the top may have been short lived.
In 2023 China lost the top spot on the list of countries whose companies populate the Fortune Global 500 list, a position it had held since toppling the USA in 2019. Is this an inflection point or will the US (one core at the top) and China exchange the position as they struggle for global economic domination in the decades ahead? This article presents six reasons for believing that China is unlikely to recover the top spot and suggests ways in which US, European, and Japanese firms can exploit China’s fundamental weaknesses in the years ahead.
In 2019, we predicted that China would likely account for more companies on the Fortune Global 500 list than any other country. That seemed like a bold prediction at the time, given that American firms had held the number one position since the list’s inception in 1995 and the U.S. economy was 50% larger than China’s. But just one year later, in 2020, China did indeed top the list, with its 124 firms edging out the U.S. at 121 (see here for the Fortune Global 500 data).
- AM Allen J. Morrison is a professor of global management at Arizona State University’s Thunderbird School of Global Management and a coauthor of Competing in and with China: Implications and Strategies for Western Business Executives (Thinkers50). Email: [email protected]
- JB J. Stewart Black is a professor of global leadership and strategy at INSEAD and a coauthor of Competing in and with China: Implications and Strategies for Western Business Executives (Thinkers50). Email: [email protected]
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World Health Organization Report: Public provision and financing of long-term care: case studies in middle- and high-income countries
As global populations age, governments around the world are investigating how to fund long-term care (LTC) in an equitable and sustainable manner. The research reported here has three objectives: (i) to identify and classify middle-income countries (MICs) and highincome countries (HICs) that have established LTC for older populations; (ii) to describe the financing features and undertake a detailed assessment of the public LTC programmes in these countries; and (iii) to identify and discuss the benefits, disadvantages and challenges of the different public LTC financing strategies, based on the experiences of high-income countries and on observations of the reviewed countries.
The public LTC financing system of 13 countries is reviewed: five HICs (Australia, Japan, Netherlands (Kingdom of the), Singapore and Uruguay), and eight MICs (China, Costa Rica, India, Indonesia, Malaysia, Serbia, South Africa and Thailand).
- Cheng, Terence C., Winnie Yip, Zhanlian Feng. 2024. “Public provision and financing of long-term care: case studies in middle- and high-income countries.” World Health Organization, Center for Health Development. https://wkc.who.int/resources/publications/i/item/public-provision-and-financing-of-long-term-care-case-studies-in-middle–and-high-income-countries
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- Published: 26 February 2024
Detection and management of coal seam outcrop fire in China: a case study
- Yang Liu 1 , 2 ,
- Xuyao Qi 2 ,
- Dayong Luo 1 ,
- Yongqing Zhang 1 &
- Jiangtao Qin 1
Scientific Reports volume 14 , Article number: 4609 ( 2024 ) Cite this article
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- Energy science and technology
- Engineering
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The outcrop fire area in Rujigou Coal Mine in Ningxia, China has been burning continuously for over 100 years. This not only results in wastage of resources but also poses significant damage to the ecological environment. Previous research on open fire detection has mainly focused on coalfield fire areas, using single method such as infrared remote sensing or surface temperature measurement, magnetic method, electrical method, radon measurement and mercurimetry. However, the outcrop fire area has migrated to deeper parts over the years, conventional single fire zone detection methods are not capable of accurately detecting the extent of the fire zone, inversion interpretation is faced with the problem of many solutions. In fire management, current research focuses on the development of new materials, such as fly ash gel, sodium silicate gel, etc., However, it is often difficult to quickly extinguish outcrop fire areas with a single technique. Considering this status quo, unmanned aerial vehicle (UAV) infrared thermal imaging was employed to initially detect the scope of the outcrop fire area, and then both the spontaneous potential and directional drilling methods were adopted for further scope detection in pursuit of more accurate results. In addition, an applicable fire prevention and extinguishing system was constructed, in which three-phase foam was injected for the purpose of absorbing heat and cooling. Furthermore, the composite colloid was used to plug air leakage channels, and loess was backfilled to avoid re-combustion. The comprehensive detection and control technologies proposed in this study can be applied to eliminating the outcrop fire area and protecting the environment. This study can provide guidance and reference for the treatment of other outcrop fire areas.
Introduction
Coal seam outcrop fire areas, if left uncontrolled, would lead to large-scale coalfield fires which seriously pollute the natural environment, cause casualties and threaten coal mine safety 1 . Coalfield fires occur in many countries around the world, such as the United States, India, South Africa and China, inducing global disasters 2 , 3 . Coalfield fires in the United States mainly hit areas such as Montana, Arizona, Wyoming, Colorado and Pennsylvania 4 . In India, coalfield fires mainly take place in Jharkhand, and in South Africa, Witbank and Sasolburg are at great risk 5 , 6 . As for China, the primarily affected region is northwest China which suffers from a lack of rain, including Inner Mongolia, Ningxia, Xinjiang, Shaanxi and Shanxi. Among them, Xinjiang and Shaanxi are the most seriously impacted, followed by Ningxia. Specific geographical locations are shown in Fig. 1 7 . The Xinjiang coalfield fire area ranks No. 1 in the world in terms of its area, and it has been burning for nearly a thousand years. According to the results of the fifth coalfield fire area survey in Xinjiang, the 40 untreated fire areas in Xinjiang cover a total area of 4.7773 million m 2 by the end of 2019 8 . The Rujigou mining area in Ningxia, one of the most serious coalfield fire areas, has been burning for more than 100 years since the Qing Dynasty. According to statistics, the Rujigou fire area releases about 15,000 tons of particulate matter and 6000 tons of sulfur dioxide annually. Under the above circumstances, numerous scholars all over the world have engaged in research concerning coal seam outcrop fires.
Geographical location map of the outcrop fire area in Baijigou Coal Mine (By EDRAW 13.0.1 https://www.edrawmax.cn ).
Methods for detecting coalfield fire areas can be roughly classified into infrared remote sensing or surface temperature measurement, magnetic method, electrical method, radon measurement and mercurimetry 9 . In May 1963, HRB-Singer Company of the United States used the airborne thermal camera RECONOFAX infrared detection system to study coal gangue coal fires. This approach marks the beginning of applying the thermal infrared remote sensing technology to detect coal fires. Furthermore, this technology proves to be feasible through experimental analysis and comparison 10 . Aiming at easing open-pit mine management, Saini combined thermal infrared and visible light images captured by drones to quickly detect and accurately locate the thermal anomaly level of open-pit mining areas 11 . Mishra et al. took advantage of the thermal imaging and remote sensing technology to detect the fire area of the Jharia coalfield in India, and verified the effectiveness of this technology 12 . Chatterjee et al. studied the coal fire dynamics of the Jharia coalfield during the 1990s based on medium-resolution satellite thermal IR data such as Landsat-5 TM and Landsat-7 ETM + data (acquired in 10.4–12.5 µm spectral region) 13 . Guha et al. employed an advanced spaceborne thermal emission and reflection radiometer to map the latest distribution of coal fires in the Raniganj coalfield. The coalfire map shows that major fires are associated with open-pit mines of the coalfield 14 . With the widespread application of UAV, it is gradually known to the public that UAV remote sensing boasts the advantages of fast data acquisition and high measurement accuracy, providing a new idea for coalfield fire detection 15 .
Magnetic detection is mainly based on the principle that changes in magnetism can reflect how temperature varies because the magnetism of rock increases with the rise of temperature 16 . Lindqvist et al. detected a total magnetic field intensity of up to 8 A/m on the coal seam of burning lignite 17 . Ide et al. successfully found a way to divide the burned and unburned coal seams for South Ute using the magnetic method 18 . Kong et al. proposed an innovative method of applying the electromagnetic radiation technology to detect high-temperature anomaly areas in the Daquanhu fire area 19 . Vaish and Pal processed data on magnetism and investigated the magnetic field anomaly of East Basuria Colliery in the Jharia coalfield in Jharkhand, India, with a view to mapping and studying sub-surface coal fires. Additionally, they calculated the residual component of the total magnetic field anomaly map of the area, so as to enhance and delineate the coal fire area 20 .
Apart from the above methods, the electrical method, which mainly includes the spontaneous potential method and the electromagnetic method, also sees extensive application in the detection of coalfield fire areas 21 , 22 . Powel is the first to discover that the electrical conductivity of carbon changes with temperature under conditions of high temperature 23 . The spontaneous potential method has been successfully applied to a shallow coal seam fire in Colorado 24 . Shao et al. conducted sandbox experiments to invert the law of potential variation in coalfield fire areas, and further verified the effectiveness of spontaneous potential detection in coalfield fire areas 25 , 26 . Shao et al. wielded the magnetic and spontaneous potential methods to delineate the extent of the fire, and proposed a composite indicator to better indicate the fire. What’s more, the spontaneous potential method has been included in the “China Coal Fire Extinguishing Regulations” 27 .
Cheng et al. exercised the isotopic radon measurement technology to detect the coal seam outcrop fire areas in Liujiamao Coal Mine and Qian’an Coal Mine 28 . Du et al. proposed a comprehensive detection and verification method for high-temperature anomaly areas using a combination of radon level, infrared imaging technology and drilling method. The test results revealed that the radon content is positively correlated with the potential temperature 29 . Sun measured concentrations and isotope compositions of atmospheric Hg in both gaseous and particulate phases on an urban site near the Wuda coalfield 30 . The measurement results demonstrated that atmospheric Hg isotope measurement functions as a useful tool for detecting concealed underground coal fires. On this basis, the isotope radon measurement technology and mercurimetry are extensively applied to coalfield fire detection 31 .
In the treatment of outcrop fire areas, techniques such as stripping, yellow mud injection, inert gas injection and loess covering are generally adopted 32 , 33 , 34 , 35 . Shao et al. used the three-phase foam and water mist technology to deal with the upper fires in abandoned roadways and loose areas and to control the coalfield fires in Anjialing open-pit mine in China 36 . Tan et al. used sodium silicate gel, a new type of pressurized moisturizing plastic sealing material, to achieve rapid cooling of the fire area and extinguish the Fukang coal fire in Xinjiang, China 37 . Zhai and Deng introduced a new type of firefighting composite gel in response to outcrop fires, and described its features, performances and applications in detail 38 . Bustamante et al. discovered that diluted bitumen and brine (combustion inhibitor), cement/slaked lime, fine sand cement and clinker/slaked lime have application prospects in preventing fires. It was also determined that bitumen/brine enjoys superior adhesion and durability properties in the coal seam 39 . Deng et al. applied composite fly ash gel to Haibaoqing coal fires 40 .
Most of the above researches involved only a single outcrop fire detection method, including infrared remote sensing, surface temperature measurement, magnetic method, electrical method, or radon measurement. Since each detection method has its own advantages and disadvantages, it is hard to accurately identify the scope of the fire area using only one of them. Besides, considering varying merits of different methods, merely using a single fire prevention and extinguishing method may not only fail to treat outcrop fire areas efficiently, but also result in resource waste 41 , 42 . Therefore, technologies regarding precise detection and economical and efficient fire prevention and extinguishing for outcrop fire areas need to be studied and put into practice urgently.
In this study, with the southern outcrop fire area in Baijigou Coal Mine as the research object, the outcrop concealed fire area was detected and treated with the multiple advanced technologies. Based on the practice, a set of effective methods and technologies were summarized. The research findings are expected to provide a reference for the detection and treatment of coal seam outcrop fire areas.
Overview of the fire area
Baijigou Coal Mine is located in the northern part of the Rujigou mining area in the middle of the Helan Mountain. It belongs to the Ningxia Coal Industry Co., Ltd. of the National Energy Group. From the aspect of administrative division, it is under the jurisdiction of the Dawukou District of Shizuishan City, Ningxia Hui Autonomous Region, China. The central geographical coordinates are 106° 08′ 00′′ E and 39° 06′ 00′′ N, and its geographical location is given in Fig. 1 . As depicted in Fig. 2 , the outcrop fire burns along the coal seam line, giving rise to a raging fire, which not only wastes valuable coal resources, but also deteriorates the environment.
Fire in the outcrop fire area before treatment.
Baijigou Coal Mine is attributed to a high gas mine. The underground 010,203 working face is the face to be mined, and the southern outcrop fire area exists near the surface above it. The surface southern outcrop fire is burning at the II 3 coal seam which is distributed in a strip. The coal seam outcrop line in the fire area is about 290 m long and 70 m wide at most. Its north side lies an open-air stripping pit, and the south side is the original mountain. The southern outcrop fire area took shape as a result of open-pit stripping. During the open-pit stripping process, signs of combustion were found near the outcrop of the southern mining area. The overall location of the southern outcrop fire area is exhibited in Fig. 3 .
Overall location of the southern outcrop fire area (By Pix4dmapper 4.8.4 https://pix4d.com.cn/pix4dmapper ).
The southern outcrop fire area is located on the west side of the 010,203 working face, the horizontal and vertical distances between them being 126 m and 121 m respectively. Under the influence of surface air leakage, the outcrop fire area gradually extends to deeper sites along the coal seam outcrop line, giving off a large quantity of open flames and toxic and harmful gases through surface fractures. At the same time, as the 010,203 working face advances, these toxic and harmful gases and high-temperature heat sources may migrate towards the 010,203 working face through leakage channels under the condition of underground full negative pressure ventilation. Worse still, these toxic and harmful gases and high-temperature heat sources, once encountering gas accumulated in the goaf, are likely to trigger gas explosion accidents and threaten underground coal mining operations (Fig. 4 ).
Sectional drawing of the southern outcrop fire area.
Treatment scheme for the outcrop fire area
Referring to the characteristics of the outcrop fire area, a treatment scheme is formulated for it (Fig. 5 ). Firstly, the infrared UAV is used to conduct preliminary detection of the high-temperature area on the surface, and the suspected fire area is preliminarily determined. Subsequently, the spontaneous potential method with strong anti-interference ability is arranged on site to detect the hidden fire area and narrow the scope of the initially delineated fire area. Finally, boreholes are constructed across the seam. For one thing, the accurate range of the fire area can be determined. For another, these boreholes contribute to the following fire extinguishing. After the completion of borehole construction, the fire gas and temperature indicators in the boreholes are measured for evaluating the development of the outcrop fire area. Once the range of the outcrop fire area is identified, the next step is to inject three-phase foam to cool down the hidden fire area by virtue of its characteristics of diffusion and accumulation. In addition, composite colloid is also poured into in the hope of plugging air leakage channels. At last, the outcrop fire area is covered with loess to prevent re-combustion.
Treatment scheme for the coal seam outcrop fire area.
Detection of the outcrop fire area
Preliminary study on the surface based on uav infrared thermal imaging.
Infrared thermal imaging, a kind of passive infrared night vision technology, is based on the fact that all objects in nature with temperatures higher than absolute zero (− 273 °C) radiate infrared at all times. Such infrared radiation carries information concerning characteristics of the object, which provides an objective basis for using the infrared technology to distinguish the temperature and thermal distribution fields of various measured targets. According to the above principle, the photoelectric infrared detector converts the power signal radiated by the heating part of the object into an electrical signal, and the imaging device can simulate the spatial distribution of the surface temperature of the object precisely. Finally, the simulation results are processed and the thermal image video signal comes into being, which is then transmitted to the display screen. Thus, the thermal image corresponding to the thermal distribution of the object surface is obtained, that is, the infrared thermal image. The UAV thermal imager is a well-performed infrared-based imager that can be controlled remotely, and it can detect high-temperature areas that are inaccessible to humans. In the light of this advantage, the M300RTK UAV thermal imager is first used to detect the surface area on the south side, so as to have a rudimentary grasp of the outcrop fire area. The M300RTK UAV boasts favorable performance and can support the ZenmuseH20 hybrid sensor that is composed of a laser rangefinder, a zoom camera, a wide-angle camera and a thermal imaging camera. With this equipment, the high-temperature area of the surface fire area can be accurately and rapidly detected.
Through online task recording, the thermal imager of the M300 RTK UAV is able to record various actions such as aircraft movement, pan-tilt pitch, photo shooting and zoom in real time. Furthermore, these recordings, if stored as route files, can be utilized at any time in future automatic inspection tasks. At the same time, it is equipped with an AI-assisted re-shoot function, which greatly improves the accuracy of automation tasks. After completing online task recording, the target area is selected from the sample frame. In subsequent automation tasks, the AI will automatically compare the target area with the current real-time picture, and correct the camera’s shooting angle accordingly, so that the same target area can be captured every time. Performances and parameters of the M300 RTK UAV are listed in Table 1 .
On September 1, 2021, two UAV flights were carried out on the southern fire area of Baijigou Coal Mine in an effort to collect topography and infrared thermal imaging data. During the test, the relevant parameters were set as follows: the outdoor temperature 18 °C, the relative humidity 70%, no sustained wind, wind strength below Level 3, the flight height of the UAV 200 m, heading overlap rate 90% and side overlap rate 90%. Besides, the parameters of the M300 RTK infrared system and the camera were adjusted accordingly, and they adopted the high gain mode. The temperature curve was set to TIFF. Under these parameters, the generated visible light numerical orthophoto with a resolution of 0.2 m is exhibited in Fig. 7 , and the detected cloud map of surface temperature imaging with a resolution of 0.4 m is shown in Fig. 6 .
Cloud map of infrared thermal imaging.
On the surface of the southern outcrop fire area, two high-temperature areas were detected. These two areas were concentrated in the slag platform on the west side (a maximum temperature of 70 °C) and in the valley on the southwest side (a maximum temperature of 65 °C). The surface of the high-temperature areas is drawn in Fig. 7 . Later on, a hand-held infrared thermometer was used for re-testing, and the temperatures of the slag platform and the valley were 52 °C and 46 °C, respectively (Fig. 8 ). Further analysis reveals that although the high temperature was detected only in the west slag platform and the southwest valley, it does not mean that the outcrop fire area only existed on the surface. As coal spontaneous combustion intensified, chances are that the fire would invade the deeper part of the mountain along the outcrop line of the coal seam. The high temperature tracked in the southwest valley is a case in point.
Surface of high-temperature areas (By Pix4dmapper 4.8.4 https://pix4d.com.cn/pix4dmapper ).
Temperature measurement by hand-held thermometer. ( a ) High-temperature Point A, ( b ) High-temperature Point B.
Delineation of the fire area based on the spontaneous potential method
In view of the fact that UAV infrared thermal imaging is limited to high-temperature detection on the shallow surface (< 10 m), it is generally used for the early detection of the outcrop fire area, and it fails to determine the location of the hidden fire source in the outcrop fire area. The authors make a comparison among current feasible fire detection methods, such as isotope radon measurement, magnetic method and spontaneous potential method. Among them, isotope radon measurement is susceptible to the properties of overlying strata, fractures, water content and weather. Besides, it corresponds to poor accuracy and weak anti-interference ability. The magnetic method proves to enjoy a good response to the burnt rock after the fire. Despite this, it cannot timely react to the high-temperature fire area that is burning. Consequently, neither of them are suitable for the detection of the southern fire area of Baijigou Coal Mine 43 . Ultimately, the spontaneous potential method was selected to detect the fire area. The spontaneous potential method is a geophysical method primarily applied to the exploration of the distribution and anomaly of spontaneous potential. By detecting the anomaly of spontaneous potential, the range of the coalfield fire area could be deduced. Based on the actual situation of the site, five detection lines were arranged with a spacing of 50 m, and measuring points were located every 5 m. At last, a total of 640 sets of spontaneous potential data were collected using a WDJD-1 multifunctional digital DC IP instrument and a pair of Cu–CuSO 4 non-polarizing electrode electrodes. The contour of the spontaneous potential anomaly area is drawn in Fig. 9 . A detailed analysis on Fig. 9 indicates that positive potential anomaly areas exist in the coordinates such as [4330120, 598280]–[433020, 598430], [4330030, 598420]–[4330160, 598520] in the absence of cluttering areas. The preliminary delineation of the fire area is given in Fig. 10 .
Contour of spontaneous potential anomaly areas in the outcrop fire area.
Comparison diagram of spontaneous potential anomaly areas in the outcrop fire area.
Verification based on the drilling detection
The location of high-temperature areas was preliminarily determined after elementary detection by thermal imaging and anomaly area determination by spontaneous potential. In order to verify the exact scope of the fire area and lay the foundation for the later fire extinguishing project, further detection was carried out through the directional drilling from the surface to the outcrop coal seam. It is noteworthy that the drilling was timely adjusted according to the detection area. A total of 15 deep holes were drilled using a φ219 mm pipe-following drill bit towards a depth of 25 m (the slope is not drilled). The φ219 mm × 8 mm casing ran under the pipe, and the total amount of drilling was 1579 m. The layout of boreholes is depicted in Fig. 13 .
A significant high-temperature area is observed near the northwest side of the 1#, 2#, 3# and 4# boreholes in the outcrop fire area. Along the northwest direction, the temperature increases remarkably, reaching the highest at the depth of 100 m.
In addition, the spontaneous combustion indicator gases (carbon monoxide, ethylene and acetylene) of coal in this area are extremely prominent. At the same time, the phenomenon that a large amount of white smoke is emitted from the borehole is observed during the process of drilling (Fig. 11 ). A thermocouple is used to measure the temperature in the borehole, and it is found that the local temperature is as high as 260 °C, which indicates that the shallowly buried outcrop coal near the high-temperature anomaly area has shown signs of combustion. The temperature measurement results are displayed in Fig. 12 . From Table 2 , it is evident that the temperatures of 9#, 10#, 11#, 12# and 13# boreholes on the south side are rather high, slightly lower than that on the northwest side. Judging from this, it is credibly inferred that the outcrop coal has spread further along the coal seam outcrop line to the north side.
White smoke emitted from boreholes. ( a ) Borehole A, ( b ) Borehole B.
Temperature of the borehole measured by the WRNK thermocouple.
Temperature measurement was also conducted in the remaining mountain supplementary boreholes (5#, 6#, 7#, 8#, 14# and 15# ), and no obvious abnormal high temperature was captured. Although a trace of coal spontaneous combustion indicator gases were occasionally detected in these boreholes, they were possibly attributed to the harmful gases that intruded into the flow field from the fire area through fractures due to the development of mountain fractures and the complexity of air leakage channels. This indicates that the fire area has not spread to the east side near the working face. Based on this, the location of the southern outcrop fire area was determined, and the potential fire area range was delineated (Fig. 13 ).
Potential fire area range of the southern outcrop fire area.
Comprehensive fire prevention and extinguishing technology
In accordance with the basic features of the outcrop fire area and the detection results of the fire area, the outcrop fire area has spread along the coal seam line to the mining area, and intensified from west to east. Additionally, the high-temperature fire source is deeply buried, and the high-temperature hazard area is large, concealed and three-dimensionally distributed, which makes it difficult for a single fire extinguishing technology to play a role. For this reason, it is of great necessity to build a comprehensive fire prevention and extinguishing system on site.
Construction of comprehensive fire prevention and extinguishing system
For the sake of achieving the four functions of water, grout, three-phase foam and composite colloid injections, a comprehensive fire prevention and extinguishing system was constructed according to local conditions (Fig. 14 ). The whole system is driven by a motor and furnished with a water supply pipeline and a nitrogen supply pipeline. The pressure of nitrogen should be higher than or equal to 0.5 MPa, and its purity is required to exceed 99.99%. As for the water supply, the pressure ought to be higher than 3 MPa, and the flow rate must surpass 20 m 3 /h. The concrete procedure for preparing composite colloid is as follows: firstly, the loess is loaded by a forklift for screening, and then transported to a mixing tank through an automatic feeding belt. After being mixed, the yellow mud is formed. Subsequently, the yellow mud, water glass and sodium bicarbonate are blended, during which the pressure is raised using a screw pump. In this way, the composite colloid is successfully prepared. In terms of the preparation of three-phase foam, it can be realized by mixing yellow mud and the foaming agent of nitrogen.
Comprehensive fire prevention and extinguishing system.
Treatment of high-temperature area
Injection of three-phase foam.
The three-phase foam technology integrates the functions of plugging, inerting, covering and inhibiting. High-expansion foam can quickly fill large tracts of fractures, and its favorable fluidity and covering ability can support fire extinguishing and cooling at hidden fire sources. The slurry from the mixing tank is transported into the pipeline through the filter screen, and 0.5–1% foaming agent is added to the slurry through the foaming agent quantitative addition pump. The slurry and the foaming agent are mixed evenly in the pipeline through the mixer before entering the foaming device. In the foaming device, nitrogen is injected and interacts with the slurry containing foaming agent to produce three-phase foam, which is later injected into the fire extinguishing boreholes through the shunt.
According to the laboratory experimental research, field industrial test, as well as the expansion coefficient of coal and rock strata (1.4), the relevant parameters are set as follows: the addition ratio of the foaming agent 1%, the foam expansion 30 times, the foam stability time ≥ 8 h, a single borehole filled with 658 m 3 yellow mud and 19,740 m 3 three-phase foam, and the foaming agent 6.6 tons. The process of pouring three-phase foam into boreholes in the field is displayed in Fig. 15 .
Pouring three-phase foam into boreholes: ( a ) preparing three-phase foam; ( b ) pouring three-phase foam.
Injection of composite colloid for air leakage channel plugging
To prevent hidden high-temperature seedlings in the outcrop coal from re-combustion due to air leakage from fractures and boreholes, it is of urgent need to fill the boreholes and fractures that have met the requirements of cooling and fire extinguishing with water–glass–gel (NaHCO 3 and water glass) in time. The composite colloid enjoys a high solid–liquid mass ratio of up to 1.5, which is 7 times that of pure yellow mud. Apart from this advantage, the composite colloid, if adsorbed with water and loess, can retain water for a long time and prolong the validity of the slurry. The sediments formed by hydrogel and loess features high solid content and good adhesion, which can effectively fill fractures and prevent the fire area from leakage-induced re-combustion. Figure 16 presents the coagulation effect of composite colloids prepared in the laboratory, and Fig. 17 illustrates the diagram of filling boreholes with composite colloid in the field.
Coagulation effect of composite colloid prepared in the laboratory: ( a ) Water-retaining property after mixing composite colloid with yellow mud; ( b ) Flip the beaker upside down on the table to observe the sedimentation effect of yellow mud.
Filling boreholes with composite colloid in the field.
In the hope of preparing high-quality and viscous composite colloid to achieve the optimal air leakage plugging and fire extinguishing effects, it is necessary to control the curing time of the colloid filling material by comprehensively combining the process flow, the required filling amount of fire extinguishing boreholes and the actual demands of fracture plugging and re-combustion prevention. Ultimately, the parameters are determined as follows: water-cement ratio 4: 1, the soda-sodium silicate-yellow mud ratio 1: 3: 20, each borehole filled with 6.6 tons of water glass and 2.3 tons of soda, and total filling space 54 m 3 .
Treatment of medium- and low-temperature areas
Considering the treatment cost, medium and low-temperature boreholes (9#–13#) are cooled by injecting yellow mud. Yellow mud boasts favorable fluidity and plugging performance, which contributes to eliminating the hidden danger of medium and low-temperature boreholes. The flow rate of yellow mud is set to 30 m 3 /h, and the water-soil ratio is 3: 1. After the injection of yellow mud, the temperatures of boreholes need to be monitored in real time. If the temperatures rise dramatically, three-phase foam needs to be injected at once for cooling. Once the temperatures drop to normal temperature and there are no signs of a rebound, composite colloid is added to block air leakage channels and prevent re-combustion. The process and technical parameters of composite colloid injection in these boreholes are consistent with those in high-temperature boreholes, which will be not repeated here.
Loess covering
After the southern outcrop fire area is cooled down and boreholes and fractures are filled, a retaining bag wall is stacked at the bottom of the northern slope. Next, the whole outcrop fire area and slope are backfilled and covered with loess. Following this treatment, a road roller is utilized to compact it immediately. The schematic diagram of loess backfilling is sketched in Fig. 18 . The area of the southern outcrop fire area to be backfilled is about 35,000 m 2 and the backfilling height will not be less than 1.0 m. Given the loose paving coefficient of 1.2, an earthwork volume of 40,000 m 3 is used. The field operation can refer to Fig. 19 .
Loess backfilling on the surface and the slope.
Loess backfilling on the slope: ( a ) Slope dumping of loess; ( b ) Slope top covering with loess.
In the early stage of treatment, spontaneous combustion in the southern outcrop fire area is severe. Through temperature measurement by means of drilling, it is detected that the temperatures of some boreholes in the delineated fire area reach up to 280 °C. The temperatures inside the boreholes are extremely high, so are the values of spontaneous combustion indicator gases such as carbon monoxide (up to 1 × 10 5 ppm). Moreover, a large amount of water vapor and smoke are observed in the boreholes of the fire area, suggesting a fierce fire before treatment.
The representative 1#, 2# and 3# boreholes are selected for continuous sampling analysis. The analysis mainly focuses on the concentration and temperature of carbon monoxide, the fire indicator gas inside the boreholes. Specifically, a portable sampling pump is used to extract indicator gas from the borehole, and a meteorological chromatograph is adopted for subsequent detection. The temperature of the borehole is directly detected by a thermocouple. The sampled data are subjected to statistical analysis, and the results are displayed in Figs. 20 , 21 and 22 . The curves of carbon monoxide in the boreholes reveal that after borehole construction, fractures in the overlying surrounding rock of the coal body are connected, which brings about an increase in air leakage channels and accelerates the formation of the “chimney effect”. This phenomenon aggravates the spontaneous combustion trend of the outcrop coal seam. The carbon monoxide concentrations in 1#, 2# and 3# boreholes all witness an upward trend, evidenced by the rising temperatures inside the boreholes. When the spontaneous combustion risk of the outcrop fire has a potential to rise, the fire prevention and extinguishing system is immediately constructed, and three-phase foam is injected. With these measures taken, the temperatures of the boreholes drop sharply and present an obvious downward trend, while the carbon monoxide concentrations lag and rebound to a certain extent. The reason behind this phenomenon is that when three-phase foam acts on the spontaneously combusting coal body, the heat of the high-temperature coal body is taken away instantaneously, and the temperature of the borehole drops rapidly. However, due to the large scope of the fire area and the considerable need for heat exchange, the fire area has not been completely extinguished. Moreover, under the impact of fractures, the spontaneous combustion indicator gas experiences no apparent changes. After thirty days of pouring three-phase foam, the outcrop fire area has been under effective control. Subsequently, composite colloid is injected into the fractures, efficiently filling the fractures in the overlying strata of the outcrop coal seam. The above treatment measures succeed in effectively controlling the fire indicator gas and the borehole temperature, holding back the re-combustion of the fire area.
Treatment effect analysis for 1# borehole: ( a ) Variation of carbon monoxide concentration in the borehole with time; ( b ) Variation of temperature in the borehole with time.
Treatment effect analysis for 2# borehole: ( a ) Variation of carbon monoxide concentration in the borehole with time; ( b ) Variation of temperature in the borehole with time.
Treatment effect analysis for 3# borehole: ( a ) Variation of carbon monoxide concentration in the borehole with time; ( b ) Variation of temperature in the borehole with time.
To test the treatment effectiveness of the outcrop fire area and evaluate the impact of the outcrop fire area on the adjacent 010,203 working face and to eliminate the threat of underground gas explosions caused by hidden danger in the outcrop fire area, samples are taken from the adjacent goaf and gas drainage boreholes after the mining of the working face. The results reveal that neither spontaneous combustion indicator gas nor high-temperature areas are detected, and the southern outcrop fire area has been extinguished, which will not pose a threat to safe mining of the working face. After the treatment is completed, grass seeds are sown in the loess backfill area to restore ecology (Fig. 23 ).
Ecological restoration after fire area treatment.
Conclusions
Through the detection and treatment of the coal seam outcrop fire area, this project provides a new method for coal seam outcrop fire control and has broad application prospects. The methods and results are summarized as follows:
Infrared thermal imaging is only applicable to the detection of high-temperature anomaly areas on the shallow surface. An integrated use of the spontaneous potential method and drilling detection can accurately delineate the range of the outcrop fire area and lay a foundation for subsequent fire area management.
The application of comprehensive fire prevention and extinguishing technologies, such as three-phase foam filling fractures for fire extinguishing and cooling, colloid injection for plugging air leakage channels, and loess backfilling for re-combustion prevention, can effectively remove the threats of outcrop fire areas and ensure the safe production of coal mines.
Data availability
The data presented in this study are available on request from the corresponding author.
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Acknowledgements
We thank the support of the National Natural Science Foundation of China (52174219), Chongqing Education Commission Science and Technology Research Program Project (KJQN202303408), and Research Project at the College Level of Chongqing Vocational Institute of Engineering (KJB202317).
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Yang Liu, Dayong Luo, Yongqing Zhang & Jiangtao Qin
School of Safety Engineering, China University of Mining and Technology, Xuzhou, 221000, China
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All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Q, L, Z and Q. The first draft of the manuscript was written by L and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
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Correspondence to Yang Liu .
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Liu, Y., Qi, X., Luo, D. et al. Detection and management of coal seam outcrop fire in China: a case study. Sci Rep 14 , 4609 (2024). https://doi.org/10.1038/s41598-024-55304-1
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Received : 03 September 2023
Accepted : 22 February 2024
Published : 26 February 2024
DOI : https://doi.org/10.1038/s41598-024-55304-1
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Doc Preview ECONOMICS ECONOMICS 101 CorporalStrawCamel3 China Noah Corporation 1 China's voracious consumer appetites are already reaching into every corner of Indonesia. The increasing weight of China in every market is a global trend, but growing Chinese, as well as Indian demand is making an especially big impact in Indonesia.
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The outcrop fire area in Rujigou Coal Mine in Ningxia, China has been burning continuously for over 100 years. This not only results in wastage of resources but also poses significant damage to ...
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