Studies on the Cleaning Potentialities of Talcher Coals by Washability

India's energy sector is primarily dependent on coal which is the abundant indigenous resource. Such dependence on coal is going to continue in the foreseeable future. Indian coals, which are of Gondwana origin, contain high ash wherein the extraneous material was intimately mixed in the coal matrix during the formation stage, causing a high level of impurities in the run-of-mine (ROM) material. These coals possess difficult to very difficult washabilaity characteristics. Beneficiation of high- ash non-coking coals of India has become the prerequisite for improving the overall economics and efficiency of power generation. The state of Orissa contains approximately 23% of India's reserves of noncoking coal. This paper describes the washability characteristics of non-coking coals from the Talcher Coalfields of Orissa aiming at 34% ash level in the clean coal as per the stipulations laid by environmental gazette notification of Govt. Of India. Conventional float - and - sink testing was carried out to determine the theoretical yield of clean coal at 34% ash content. The washablity data was used for prediction of practical yield which may be achieved by using a Jig washer. Based on the simulated results a conceptual flow sheet was developed

Studies on the Cleaning Potentialities of High Ash Non-coking Coal of lb Valley Coalfields

Coal is the main source of energy for the development of Indian economy and will remain as the most economically viable option for power generation. About 71% of country’s total power generation is in the form of thermal, out of which more than 60% is coal-based. Indian coals contain high ash content and are difficult-to-wash and it is essential to beneficiate them to the required level acceptable to different end users. This article describes the washability characteristics of a typical non coking coal from Ib Valley Coalfields aiming at 34% ash level for power generation through pulverized fuel combustion. Conventional float-and-sink testing was used to determine the yield of clean coal. A suitable flow scheme for beneficiation of the non-coking coal was suggested

Study on Beneficiation behavior of IB Valley Coal

The mineral matter in coal has several detrimental effects on coal utilization. It affects almost every aspect like mining, handling, transportation, utilization etc. With the depletion of good quality coal attention has been diverted towards use of low grade coals with high ash. Indian thermal coals known for their wide variations in nature are categorized as difficult to wash. It necessitates suitable beneficiation techniques to reduce the burden in most combustion cleaning systems. Due to heterogeneity inorganic and organic contains of coal are difficult to determine which causes environmental problem in its usage cycle. The paper describes beneficiation of IB valley coal using conventional float sink method and characterization study of a suitable specific gravity cut (determined by washability curve) to determine its washability and combustion behavior. Result of the study reveals that quartz content of washed coal with 34% ash yield, as mandated by the Ministry of Environment and Forest (MOEF) for the use of coal in power plants, is reduced to half of that of the raw one. Quartz is the most abrasive mineral in coal and its reduction proportion along with Kaolinite obviously signifies efficient, economic and ecofriendly utilization. The composition of the major minerals viz., quartz and Kaolinite also favors formation of ash of refractory nature during combustion

Sedimentation Studies on Effect of Some Industrial Flocculates on Indian Non-coking Coal Fines

Washing of Indian non-coking coal is coming up in a big way to meet the Government stipulations. The coal industry is washing about 120 million tonnes of non coking coals and has planned to enhance 250 million ton in five year times. Depending on the washability characteristics and coal washing equipment top size intake, ROM coal is usually crushed to a desired top size. The different process of handling and washing generate fines (below 500 µm) to the tune of around 10 percent of whole coal. In the course of coal washing the fines are discharged along with process water and sent to the thickeners for recovery. This coal fines, associated clay, mineral matter particles depending on the ash percentage either mixed with clean product or sent to the rejects. The processed water as such cannot be used as recirculation water, unless mostly suspended fines are settled down and separated in the thickener. To enhance the settling rate of the suspended colloids, some chemical polymeric flocculants is industrially used. Depending on the flocculent, coal surface properties, associated clay, mineral matter particles settling efficiency varies greatly. Present studies reflect some of the findings on the sedimentation rates of flocculants

Effect of Conditioning on the Beneficiation of Dilute Coking Coal fines by froth flotation

The coal preparation plants produce large quantities of coal slurry having very dilute pulp density (3 to 5 percent) during desliming of coals. Froth flotation is a universally accepted process for the beneficiation of coal fines, but the process being sensitive needs careful monitoring of the process variables. One of the prerequisites for flotation of slurry is to have an effective conditioning for proper adsorption of reagents with the coal particles. In this paper attempts have been made to upgrade low pulp density coal fines by designing a suitable conditioner and carrying out laboratory flotation test by varying some important process variables like pulp density, reagent (collector and frother) dosage. The effects of these variables on the results of flotation have been studied. Correlations have also been developed between yield/ash percent of concentrate and the variables through regression analysis. A statistical analysis is presented to study the effects and interactions of the variables

Characteristics and concepts of washing low volatile coking coals of jharia coalfields

Indian coals of Gondwana origin are heterogeneous in nature and constitute about seven percent of the world’s proven coal reserves. As on today, the total reserves of coal in india is 277 billion tones. Out of which about 83% constitute non-coking coal, 14% coking coal and the rest are others. Coking coal is an essential input for production of Iron & Steel through blast furnace route. To save steel industry facing acute dependence on imported coking coal, domestic availability of coking coal in desired quality has become imperative. The good quality coking coals of the upper seams are fast depleting leaving behind the inferior quality lower seam coal. The lower seam coals presently being mined are mostly low volatile coking coal (LVC). They constitute about 50% of the total coking coal reserves in India. These coals are characterized by high raw coal ash content and poor washability characteristics. In India, the first attempt to beneficiate the coking coals had come in to the horizon mainly to meet the requirements of steel industries and a chain of coking coal washeries had come in to existence since earlier 1950’s. Of the existing coking coal washeries, only three are less than 20 years old, whereas most are 40-50 years old. Beneficiation of the lower seam coals in the existing washery circuits (2 or 3 product) does not yield requisite quality demanded by the steel sector of the country and thus almost entire production is being supplied to the thermal power stations. This paper presents the detailed laboratory investigations in terms of characterization and washability followed by pilot plant studies carried out on typical high ash, difficult-to –wash LVC coal samples of Jharia coalfields from both Eastern & Western sector and suggests the concept of beneficiation for the improvement in the quality of ROM coal. The coking propensities and the petrographic analysis of the clean coal strongly support its use for the metallurgical purposes

Utilization of High Ash, Low Volatile Coking Coals of Jharia Coalfield, India for Coke Making

India is having limited resources of coking coal, an essential input for production of iron and steel especially through blast furnace route. The coking coal sources are presently from the lower seams of Jharia coalfield, which are high in ash content and low in volatile matter and difficult to wash. This paper describes the washability characteristics of a typical coking coal from the Eastern and Western Jharia coalfields aiming at 18% ash level in the clean coal mainly to meet the specifications of coke making for blast furnace use. Conventional float-and-sink testing was used to determine the yield of clean coal for the coarser fraction, while the coal fines was subjected to flotation. The theoretical recovery of clean coal for the coal tested from Eastern and Western Jharia coalfields are 27% and 19.7% at the stipulated ash content. The coking propensities and the petrographic analysis of the clean coal strongly support its use for coke making either directly or as a blend with imported coal

Evaluation of Quartz Reduction by Coal Cleaning for Thermal Utilization of an Indian Coal

In Indian coals, quartz is abundantly found and its proportion usually varies from 5–20% by weight. Beneficiation of high-ash thermal coals of India has become the prerequisite for improving the overall economics and efficiency of power generation. A detailed survey of literature reveals that no systematic work has been done of beneficiated coal for Indian coals with respect to quartz, as also for correlation with abrasion. Therefore, to understand this effect different sizes of crushed coal were subjected to float-sink treatment at specific gravities in the range of 1.30– 1.80. This study highlights the systematic method of measuring crystalline silica (α-quartz) in bulk coal samples using NIST-SRM 1878a as a calibration standard withmore accuracy by FT-IR as well as distribution of quartz in various screen sizes, float-and-sink fractions, for both the feed and clean coal. The results show that there is a linear relationship between ash % and quartz % with respect to specific gravity for all screen sizes. Characterization of the feed and clean coal with respect to quartz was also done using XRD, SEM, and XRF spectroscopic techniques to evaluate the reduction behavior of quartz during the coal-cleaning process

Studies on the Segregation of Minerals in Different Size and Gravity Fractions While Treating Indian Coal

Gondwana coal makes up to 98 per cent of the total reserves and 99 per cent of the production of coal in India. These coals are intimately mixed with mineral matter, causing a high level of impurities in the run-of –mine (ROM) coal. Beneficiation of high – ash non-coking coals of India has become the prerequisite for improving the overall economics and efficiency for downstream utilization industries. The association between specific mineral and organic constituents in a typical non-coking coal sample form the Eastern Coalfields, India was studied. For this, raw coals were fractionated by size and density and the variation of major minerals with respect to size and density was examined. Mineral species were identified by X-ray diffraction. The results showed that the concentration of quartz and kaolinite increases with increase of gravity of the coal while concentration of siderite is much lower size fractions of the coal