John Finlay Group Of Companies

Case Studies

COAL GASIFICATION-ASSOCIATED ADVANTAGES AND CHALLENGES (Overground and Underground Gasifiers)

Authors are with John Finlay India Pvt Ltd: Om Prakash- Advisor Coal & Minerals Beneficiation Aadil Keshwani- Managing Director Preamble: We are in an era of depleting resources for petroleum and natural gas due to the rapid growth of our population and demand for gradually improving the quality of our day-to-day life. The invention of Coal Gasification is to make up for the shortage of liquid and gaseous fuels. Coal Gasification is a technical process of converting coal into synthesis gas known as SYNGAS a mixture of carbon monoxide, hydrogen, carbon dioxide, and other minor constituents by reacting the coal with oxygen, steam, and carbon dioxide. This process takes place in a gasifier at a pressure greater than 30 Bar and a temperature typically reaching 1225 Degrees C. TYPICAL INTEGRATED COMBINED CYCLE OF COAL GASIFICATION: The undermentioned typical equipment flow diagram depicts the use of SYNGAS for the generation of electrical power with the following features: Secondly, the hot combustion gas from the gas turbine is sent to the heat recovery steam generator which produces steam, which in turn drives the steam turbine for additional generation of electricity. This demonstrates a typical combined cycle where gas and steam turbines both are in operation for the utilization of gas as well as steam. UNDERGROUND COAL GASIFICATION (UCG): Underground coal gasification is essentially the same chemical conversion process used in surface coal gasification plants to convert solid coal into a mixture of useful gases known as SYNGAS. The main difference is that surface gasification occurs in a manufactured gasifier (reactor) whereas the gasifier for underground is a natural geological formation containing unmined coal. Vertical wells called injection wells and producer wells are drilled into a coal seam and linked together horizontally within the seam. Coal ignition is initiated through the use of an electric coil or gas firing near the surface of the coal seam. A compressed gasification agent (air or oxygen) is pumped into the injection well to allow for the combustion of coal. Combustion produces heat, carbon dioxide, and some SYNGAS through partial combustion. Through a series of chemical reactions involving pressure, heat, and carbon dioxide from combustion, steam (generated from water in the coal) and the carbon from the coal SYNGAS is produced. The gasification channel is normally divided into three zones: – Combustion / Oxidation Zone – Reduction Zone – Dry Distillation & Pyrolysis Zone In the oxidation zone, a multi-phase chemical reaction occurs involving oxygen in the gasification agents and carbon in the coal. The highest temperature occurs in the oxidation zone, due to the large release of energy during the initial reactions. In the reduction zone, the main reactions involve the reduction process. Within the distillation and pyrolysis zone, the coal seam is decomposed into multiple volatiles. Requisite Quality of Coal for Gasification: – Coal having volatile contents of around 35 % is advantageous – The lower rank of coal with a higher % of volatile matter reacts well with oxygen and steam to facilitate the reaction to take place in the gasifier. – Coal with a low moisture % is always beneficial. – The ash % around 30 with infusible ash is always preferred. Hence washed coal is primarily the best for gasification. – Fusible ash tends to serious clinking phenomena in the gasifier and is bound to slag with the lining of the gasifier. For dislodging clinkering, extra force is needed which causes undue loss of carbon in refuse. – Strongly coking coals are not recommended for gasification whereas the use of slightly coking coal in a gasifier is advantageous. Advantages of Underground Coal Gasifier (UCG) Vis-à-vis Overground Gasifier: – UCG offers the potential to use the energy stored in the coal deposits that are uneconomical to mine out the coal by conventional methods. – There is no need to mine out the coal, safety hazards associated with underground coal mining are eliminated. – UCG reduces significant disorders such as surface disturbances, land use conflicts, and avoidance of greenhouse gas production associated with coal mining. – UCG is a carbon capture process as it delivers an enriched CO2 stream suitable for carbon capture and storage. – UCG is a lower carbon-emitting process for power generation when compared to conventional coal-fired power stations. – Capital expenditure for UCG projects can be substantially lower than equivalent surface gasifier projects. Challenges of UCG System Vis-à-vis Overground Gasifier: – High chances of contamination of groundwater in the UCG system. – UCG operation cannot be controlled to the same extent as surface gasifier which poses the risk on account of high temperature and pressure in the cavity. – Some of the coal in UCG may have geologic and hydrologic features that increase environmental risks to unacceptable levels. – The economics of UCG-based power plants are not available as there is no UCG power plant in operation. – UCG carries huge environmental and geological risks. – The void created by UCG may cause significant deformation both in the remaining coal and surrounding rocks. – Heating, quenching, water flux, and potential roof and wall collapse may seriously compromise the integrity of the cavity. These are difficult to predict.  – The high ash content of Indian Coal poses significant technical challenges for gasification process. – The UCG system cannot have a facility for washing the coal to meet the ash % requirement. – Underground gasifiers may not be as efficient as overground gasifiers. COAL GASIFICATION PLANTS IN INDIA: India’s foray into Coal Gasification began in the 1960s with the establishment of the Sindri Fertilizer Corporation of India (FCI) Plant. However, significant progress has been sporadic. Presently notable projects include: JINDAL STEEL & POWER LIMITED (JSPL), has been operating a coal-based Direct Reduced Iron (DRI) plant in Angul, Odisha since 2014. BHARAT HEAVY ELECTRICALS LIMITED (BHEL), A pilot plant at Tiruchirappalli generating 6.2 MW, facing challenges with high ash coal. THERMAX A Coal-to-Methanol Pilot Plant in Pune, funded by the Department of Science and Technology under NITI Aayog. TALCHER FERTILIZER LIMITED (TFL),

COAL GASIFICATION-ASSOCIATED ADVANTAGES AND CHALLENGES (Overground and Underground Gasifiers) Read More »

SALIENT FACTORS GOVERNING THE FLOTATION OF COAL

The authors are with John Finlay India Pvt Ltd. Om Prakash- Advisor Coal & Minerals Beneficiation Aadil Keshwani- Managing Director Preamble: Froth Flotation is the most efficient method of beneficiating coal having a particle size below 0.5 mm. Intensive mechanization and poorer quality of seams now left for exploitation, make beneficiation of coal particle size (-) 0.5 coal mm unavoidable. If this fraction is not treated by froth flotation, the losses can be as high as 15-20% of ROM coal. Besides this, the untreated coal fines when mixed with washed coal appreciably increase its ash content. This paper discusses the salient factors affecting the flotation of coal. John Finlay and its partner companies have Flotation Machines well covered in the product range with the following advantages of the Flotation Machine. Advantages: Self-Aeration Mechanical Agitation: Designed specifically for the flotation of (-) 0.5 mm coal, the John Finlay Flotation Machine series utilizes self-aeration mechanical agitation, ensuring efficient and effective processing. No blower is required for forced aeration. Hence, simplified design for achieving optimum performance. Uniform Bubble Distribution: The machine provides a uniform distribution of flotation reagents and then the creation of bubbles, resulting in excellent flotation selectivity and reliable operation, making it ideal for precise coal separation. Low Energy Consumption: Among similar John Finlay, the Flotation Machine series stands out for its low energy consumption and high aeration rate, contributing to cost-effective and sustainable consistent operations and performance. Proven Performance: With over 2,000 units promoted and in operation, is recognized as an ideal upgrade and replacement for older flotation machines, delivering enhanced performance and reliability. Factors Governing the Flotation of Coal: Rank of Coal and Extent of Oxidation: The rank of coal is a very pertinent factor for flotation. Low-volatile coal is easier to float than most high-volatile coal. Anthracite is more difficult to float than highly volatile bituminous coal. Lignite is the least floatable to all coals. Oxidation adversely affects the flotation characteristics of coal. Even easily floatable coal becomes difficult to float post oxidation of coal. If the surface of coal is oxidized, then it behaves like a shale material. With judicious selection and application of flotation reagents, the flotation of oxidized coal can be managed up to a certain extent. Flotation Pulp Preparation: Today mining of coal is fully mechanized and the emphasis is there to raise production as much as possible. In this process of maximizing production, the overburden of mine also becomes a part of production. Due to this flotation feed pulp preparation also varies in nature and proportion as feed coal to washing plant comes from different sources. To feed consistent quality raw coal to the flotation circuit, the facility of blending feed coal from different sources in washery premises must be provided before flotation. Particle Size of Coal in Pulp: The particle size of coal for froth flotation is very important. From laboratory investigation, the established optimum particle sizes for flotation range from 48 mesh to 150 mesh. It is not economical flotation to have a particle size above 0.5 mm. If the recommended particle size range is not fed to flotation, then it affects recovery and flotation time. Pulp Density: If the feed coal size is finer, then 10 % solid by weight is recommended for flotation feed pulp. This is in practice if the coal size is (-) 0.5 mm and below. However, the flotation pulp density range varies from 10 % to 15 % solid by weight. The best way to establish pulp density of flotation is by testing the coal representative coal sample in the washery laboratory flotation machine and then optimizing the pulp density. It is advisable to use these inputs on pulp density for flotation plants. Water Characteristics and pH Level: To achieve an efficient flotation process fresh water and neutralized water will give the optimum performance of flotation process. The best clean coal yield % and optimum recovery % are obtained when water pH ranges from 6.0 to 7.5. Ash % of clean coal will increase with the increase of water pH from the recommended level. Ultra fines in flotation feed pulp will decay the performance of flotation. Quality of Flotation Reagents: Flotation reagents such as Frother, Collector, and Depressant are expensive for the flotation process. The quality of these reagents is to be selected judiciously. The doses of these reagents can be optimized by conducting laboratory tests in a washery laboratory and then with a scale-up factor on doses for flotation plant can be in practice. Reagent doses vary as per feed characteristics of coal for flotation. Normally, conditioning is done with the collector at thicker pulp, 30 % solid by weight. This will optimize the use of collector dose consumption. Postconditioning, the pulp is diluted to 10 % solid by weight in a pulp density adjusting tank and then gravitates to the flotation tank. Flotation at 10 % solid by weight optimizes the yield and recovery from flotation. Frother can be added directly to the first cell of the flotation cell bank. Sometimes, Depressant is used in case of selective flotation by depressing silica and other gangue materials in the feed coal. Conditioning and Flotation Time: The flotation performance depends upon conditioning time and flotation time at respective pulp density. Conditioning time varies from 2 minutes to 4 minutes depending on feed coal characteristics.  Flotation time varies from 3 minutes to 5 minutes. This also depends on the feed coal characteristics. Conditioning time and flotation time are prerequisites for flotation and these inputs are decided by laboratory tests in a washery laboratory flotation machine. Scale-up factors on conditioning time and flotation time on laboratory inputs make the basis for commercial flotation plant operation. Flotation Time & Flow Rate: Flotation time and flow rate are interlinked and depend upon flotation operation. For good flotation, sufficient long time is given to the particles to enable them to come in contact with air bubbles. This criterion is important in selecting the number of cells and the bank

SALIENT FACTORS GOVERNING THE FLOTATION OF COAL Read More »

Case Study: Xinjiang Zhonglun Dry Coal Sorting Project

The Xinjiang Zhonglun Coal Sorting Project, situated in the Gaochang district of Turpan City, Xinjiang, addresses the unique environmental challenges of the region. With an annual production capacity of 5 million tons of raw coal, this project is focused on efficient and sustainable coal processing. Given Turpan’s perennial water shortages and drought conditions, traditional coal-washing methods are not feasible. To overcome these challenges, Xinjiang Zhonglun Coal Sales Co., Ltd. has implemented advanced intelligent dry coal sorting technology.

Case Study: Xinjiang Zhonglun Dry Coal Sorting Project Read More »

Case Study: Jiyuan Coal Mine Dry Coal Sorting Project

The Jiyuan Coal Mine Dry Coal Sorting Plant in Tongzi County, Zunyi City, Guizhou Province, is a state-of-the-art coal preparation facility designed to process 1.8 million tons of raw coal annually. This plant services the coal produced by Jiyuan, Guancang, and other surrounding coal mines. The plant leverages intelligent dry coal sorting equipment by employing advanced X-ray identification technology to produce high-quality coal products.

Case Study: Jiyuan Coal Mine Dry Coal Sorting Project Read More »

Case Study: Maomao Mountain Coal Mine, Shanxi Province – AI-Dry Coal Sorting and Kaolin Extraction

Maomao Mountain Coal Mine, located in Shanxi Province, is renowned for its 1/3 coking coal. With an annual coal output of approximately 5.00 Mt, the mine is poised for expansion to 10.00 Mt per year. The coal seams are rich in gangue and kaolinite, presenting significant sorting challenges. Maomao Mountain invested in a state-of-the-art dry coal sorting and kaolinite beneficiation system to enhance economic efficiency and streamline operations.

Case Study: Maomao Mountain Coal Mine, Shanxi Province – AI-Dry Coal Sorting and Kaolin Extraction Read More »

Reject Recovery: Wealth from the waste

Guizhou Panjiang Clean Coal Co., Ltd. has leveraged the capabilities of the Circle Series machines to process small particle materials and recycle piled Rejects effectively. By implementing the “screening + sensor-based dry coal sorting” process, the Shanjiaoshu Mine has achieved comprehensive utilization of Rejects, enhanced economic benefits, and promoted environmental sustainability.

Reject Recovery: Wealth from the waste Read More »

Case Study: Laogongyingzi Coal Mine of Pingzhuang Coal Industry in Inner Mongolia

The Laogongyingzi Coal Mine coal preparation plant, located in Inner Mongolia, traditionally relied on a screening, picking, and crushing process system. The raw coal was classified into 80 (70) mm and 30 mm grades, with manual selection of large coal blocks. This method posed significant challenges, including high dust and noise levels, safety hazards, labor intensity, and low sorting efficiency. To address these issues, the mine has upgraded its system with an advanced dry coal sorting technology.

Case Study: Laogongyingzi Coal Mine of Pingzhuang Coal Industry in Inner Mongolia Read More »

Case Study: Guineng Group Hebian Coal Industry

Guineng Group Hebian Coal Industry is located in Duge Town, Shuicheng District, Liupanshui City, Guizhou Province. With a production capacity of 900,000 tons per year, the mine faces challenges due to high Reject content and poor quality of raw coal, leading to low market prices and the necessity of transporting coal to distant preparation plants for washing. To address these issues, Hebian Coal Mine has implemented a dry coal sorting system at the wellhead.

Case Study: Guineng Group Hebian Coal Industry Read More »

Case Study: Xinyan Coal Mine Underground AI Dry Sorting System Solution

Xinyan Coal Mine, located in the southwest of Zhongyang County, Shanxi Province, has a designed production capacity of 2.40 Mt/a. The mine faces challenges due to thin coal seams, resulting in roof cutting and bottom breaking during mining, leading to high reject content. The current system causes increased pressure on the main transportation capacity and burdens the coal preparation plant. Xinyan Coal Mine implemented an advanced AI-driven dry sorting system to address these issues.

Case Study: Xinyan Coal Mine Underground AI Dry Sorting System Solution Read More »