Non-coking Coal Research Articles

Alginic acid‐g‐poly(N‐vinylformamide) graft copolymer: Synthesis, characerization, swelling, and flocculation property

AbstractThe graft copolymer of N‐vinylformamide with alginic acid was synthesized by free radical polymerization using potassium peroxymonosulphate and thiourea as redox pair in inert atmosphere. The optimum conditions for maximum grafting have been determined by varying the concentrations of N‐vinylformamide, potassium peroxymonosulphate, thiourea, sulfuric acid, alginic acid as well as time duration and temperature. The grafting parameters increase up to the certain concentrations of N‐vinylformamide, potassium peroxymonosulhate, thiourea, and hydrogen ion while thereafter grafting parameters decrease. The effect of alginic acid concentration on grafting parameters has been observed to decrease continuously. It has also been found that grafting parameters increase up to certain time and temperature, respectively, and thereafter decrease. The swelling properties of graft copolymer in terms of swelling ratio and percent swelling are investigated. Flocculation property of pure and grafted sample for both coking and noncoking coals is also investigated for the treatment of coal mine waste water. The graft copolymer has been characterized by Fourier transform infrared spectroscopy as well as thermogravimetic analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Beneficiation of high-ash, Indian non-coking coal by dry jigging

Indian coals, which are of Gondwana origin, contain high amounts of mineral matter, wherein the extraneous material was intimately mixed in the coal matrix during the formation stage, causing a high level of impurity in the run-of-mine (ROM) material. These coals possess difficult to very difficult washability 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 use of dry cleaning systems in India for beneficiation of non-coking coals has gaining renewed interest recently. The benefit of the dry beneficiation process is to exploit the given resources while providing a more reliable and consistent quality fuel with a low operating cost. M/S Allmineral has introduced a technique for the dry beneficiation of coal, which is being tried in India for the treatment of high-ash non-coking coals. The first commercial air jig of 50 t/hr capacity was installed and commissioned to beneficiate high-ash coals of 40 × 5 mm feed with an ash content of 40%; a clean coal product of 33% ash was produced and is being used for a sponge iron plant.

Direct Reduction Behaviors of Composite Binder Magnetite Pellets in Coal-based Grate-rotary Kiln Process

Directly reduced iron is an imperative burden for EAF (electric arc furnace) to make good quality and special steel. As an alternative of direct reduction processes, an innovative coal-based direct reduction of composite binder magnetite pellets in grate-rotary kiln has been developed at Central South University and put into operation. A study of the direct reduction behaviors of composite binder magnetite pellets was carried out in a simulating coal-based grate-rotary kiln process in this paper. Preheated pellets made of magnetite concentrate and composite binder and fired oxide pellets containing bentonite as binder were directly reduced using non-coking coal as reductant in a tube furnace, and their reduction behaviors have been demonstrated by measuring reducibility, variations of compress strength, porosity, phases changes and micro structure under XRD, SEM and optical microscopy. It is shown that preheated pellets possess much better reducibility than fired oxide pellets. Superior reducibility of preheated pellets should be ascribed to their higher effective diffusivity due to higher porosity. The compressive strength of preheated pellets climbs quickly after reducing for 30 min and achieve a high value at the end of reduction, leading to smooth and intact metallized pellets whereas the compressive strength of metalized pellets from reducing of fired pellets is much lower, more cracks and fractures being formed. The preheated pellets possess self-curing function because of the multiple functions of composite binder, eliminate cracks and fractures and keep pellets intact during reducing, depressing reduction degradation and preventing accretion in rotary kiln.

Coal resources in Russia and abroad: A review

Existing information regarding the confirmed and predicted coal reserves in the world and in Russia and regarding current and predicted coal exporters and importers is analyzed. Russia is the world leader in terms of coal resources. Russia’s apparent deficit of coking coal for domestic use will be eliminated by 2014, thanks to the introduction of the El’ginsk, Elegestsk, and Usinsk deposits and the blast-furnace injection of coal dust made from noncoking coal.

A Modified Godbert Apparatus for Determining Optimum Level of Beneficiation for Indian Non-Coking Coal for Power Generation

The characteristics of coal depends on different parameters like rank, moisture, mineral matter content, macerals composition, etc. The combined effect of these characteristics governs the combustion behavior of coal in the furnace. The Indian ROM coals contain higher inherent mineral matter and a majority of these coals are used for power generation without any beneficiation; even though the environmental gazette notification of the Govt. of India requires all coal suppliers to install coal washeries. Combustion behavior of coal is evaluated by one of the following techniques: i.e., TGA, drop tube furnace, fuel efficiency test rigs, etc.; however, all these following techniques are costly and time consuming. The Godbert apparatus, which is low-cost simple equipment, can be used to evaluate the combustion behavior of coals. The minimum ignition temperature (the lowest temperature at which an ignition/explosion is observed as a flame) was determined for the ROM coal and density separated/various ash-content fractions up to 700°C. The results indicated that the coal containing up to 58% ash showed good flame/burning behavior. This study should provide guidance to coal washery operators to determine at what ash level the coal should be washed so that it can give better combustion rather than taking the ash value of 34% set up by the Indian Government.

India at the crossroads

India, which produced nearly 67 Mt steel in 2010, aims to produce, in the near future, more than 100 Mt/year and to become, after China, the second largest steelmaker worldwide. To do this, India benefits from large iron ore reserves, especially of high-grade hematites, which presently constitute the largest amount of the local consumption as well of the exports. For the future, however, it will be necessary to beneficiate the large reserves of lower-grade iron ores, especially the magnetites. Furthermore, the question of the amount of the Indian iron ores available for export will have to be considered. India also has very large coal resources but, unhappily, mainly in non-coking coal, and often with high ash content: this is the main problem of the Indian iron and steel industry, to select the best routes and processes to make steel. The Indian iron and steel industry has to choose between: the conventional route based on the Blast Furnace and Oxygen Converter, which implies increasing the imports of high-grade coking coal, mainly from Australia; various routes based on local Indian coals, such as: (a) COREX or FINEX processes to produce liquid hot metal, or (b) direct reduction processes, either based on natural gas where it is available, or on local coals, presently mainly in rotary kilns (but with serious problems of energy efficiency and environmental pollution, in spite of the large present development), or based on coal gasification processes (such as MXCOL or ITmk3 processes). Finally, another special feature of the Indian iron and steel companies, specially of the largest private ones such as Tata, Essar and JSW (Jindal), is their development outside of India, which means the control of some 18 Mt steel/year, aiming to reach about 25 Mt/year in the near future!

Synthesis of graft copolymer (CmgOH-g-NVP) and study of physicochemical properties: Characterization and application

The synthesis of graft copolymer (partially carboxymethylated guar gum-g-N-vinyl-2-pyrrolidone) is carried out in nitrogen atmosphere using potassium peroxymonosulphate and glycolic acid as redox system. The effect of reaction variables including the concentration of N-vinyl-2-pyrrolidone (8 × 10 −2 to 24 × 10 −2) mol dm −3, potassium peroxymonosulphate (6 × 10 −3 to 22 × 10 −3) mol dm −3, glycolic acid (0.6 × 10 −3 to 4.0 × 10 −3) mol dm −3, sulphuric acid (1 × 10 −3 to 3 × 10 −3) mol dm −3), partially carboxymethylated guar gum (0.6–1.4) g dm −3 as well as time duration (60–180) min and temperature (30–50) °C has been studied. The water swelling capacity of graft copolymer is investigated. Flocculation property for both coking and non-coking coals is studied for the treatment of coal mine waste water. The graft copolymer has been characterized by Fourier transform infrared spectroscopy and thermogravimetic analysis.

Studies on the Reduction–Swelling Behaviors of Hematite Iron Ore Pellets with Noncoking Coal

Studies on the reduction and swelling behaviors of fired pellets, made by mixing hematite iron ore fines of −100, −18 + 25, and −10 + 16 mesh sizes in different proportions, were carried out with low-grade coal in the temperature range of 850–1000°C with an aim to promote the massive utilization of fines in ironmaking. The rate of reduction in all the fired iron ore pellets increased markedly with an increase in temperature up to 1000°C and it was more intense in the first 15-min soak time. Relatively higher reduction rates and swellings/shrinkage were observed in the pellets made by the addition of larger size (+100 mesh) particles in the matrix of −100 mesh size fines. In general, highest swelling was observed in the fired pellets at a reduction temperature of 850°C, followed by a decrease at 900°C. At both these temperatures, the percentage of swelling increased with reduction time up to the range studied (120 min). The fired pellets reduced at temperatures of 950°C and 1000°C, showed shrinkage, and the extent of this shrinkage increased with increase in exposure time at 950°C. The percentage swelling/shrinkage in the fired pellets was found to be related to their crushing strengths and porosities.

Present and future of direct reduction in India and the rest of the world

The installed capacity and actual production of DRI in India and the rest of the world has grown at a frantic pace in the last five to ten years. Today, India is the largest producer of DRI and one of its unique features is that both non-coking coal as well as natural gas is used as the reductant. Furthermore, gasification of non-coking coal and use of the resulting 'synthetic gas' in shaft furnace DR units is also being attempted. Another innovation in India is the direct use of DRI fines in small capacity induction furnaces. This has helped disburse the steel industry to various parts of India. The only negative aspect of the proliferation of DR plants in India has been the inadequate attention paid to the environment, particularly by small coal-based units.

Use of the innovative Romelt technology to process iron-bearing wastes from mines and metallurgical plants

It is proposed that waste products formed at metallurgical plants be recycled by using the Romelt process – a continuous one-stage method of obtaining pig iron from iron-bearing raw materials in a slag bath with the use of abundant inexpensive grades of non-coking coals. Calculations are performed to determine the main economic indices of a project involving the construction of a Romelt facility at an integrated metallurgical plant.

The Utilization of Non-coking Coal by Flotation Using Non-conventional Reagents

Flotation studies of non-coking coal using two non-conventional collectors, namely Polanga and Mahua oil, containing both saturated and unsaturated fatty acids are investigated. The effect of oil concentration, surface modifier, and dispersant are studied. The results of the studies have shown that despite their higher consumption, both of the oils can be used as the flotation collector. The ash level could be reduced to 22% with 60% yield from a non-coking coal containing 40.2% ash. The results of the studies are comparable with the flotation studies of conventional reagents, such as diesel oil and methyl iso-butyl carbinol. Electro-kinetic measurements and x-ray diffraction studies are carried out to understand the surface properties and minerals present in non-coking coal.

A study toward the physicochemical properties of graft copolymer (partially carboxymethylated guar gum‐g‐N,N′‐dimethylacrylamide): Synthesis and characterization

AbstractUnreported graft copolymer of N,N′‐dimethylacrylamide (DMA) with partially carboxymethylated guar gum (CmgOH) has been synthesized and the reaction conditions have been optimized for affording maximum grafting using a potassium peroxymonosulphate (PMS)/thiourea (TU) redox initiators under nitrogen atmosphere. The study of graft copolymerization has been performed to observe maximum value of grafting parameters except percentage of homopolymer by varying the concentrations of DMA, PMS, and TU. The grafting parameters increase continuously on increasing the concentration of DMA from 8 × 10−2 to 24 × 10−2 mol dm−3, PMS from 5 × 10−3 to 21 × 10−3 mol dm−3, and TU from 1.6 × 10−3 to 4.8 × 10−3 mol dm−3. The optimum temperature and time for grafting of DMA onto CmgOH were found to be 35°C and 120 min, respectively. The water‐swelling capacity of graft copolymer is investigated. Flocculation property for both coking and noncoking coals is studied for the treatment of coal mine waste water. The graft copolymer is characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Importance of the textural characteristics of inert additives in the reduction of coal thermoplastic properties

Seven carbonaceous materials of different origin were chosen in order to study the influence of their porous structure on the modification of the thermoplastic properties of a bituminous coal. The materials included were: two non-coking coals, a petroleum coke, coke fines, two residues from tyre recycling and a bituminous residue. The materials were heat-treated to 900 °C to prevent any chemical interaction between the volatiles evolved during co-carbonization. The thermoplastic properties of blends that contained 10 wt.% of additive were measured by means of the Gieseler test. Microporosity was measured by CO 2 adsorption at 273 K, whereas meso and macroporosity were determined by means of mercury porosimetry. The results of the porous structure assessment are discussed in relation to the modification of coal plasticity.

Tuyere failure analysis in Corex process

Corex is an alternative smelting reduction ironmaking process where non-coking coal and pure oxygen is used instead of coke and air. The temperature of the tuyere region is much higher than in a blast furnace, and sustainability of tuyeres is a major challenge. At JSW Steel Ltd, almost 15% of the total shutdown is due to burnt tuyere replacement. A detailed analysis of tuyere failure and process parameters effecting tuyere burning was conducted to understand the failure mechanism and the root causes. A common reason does not exist for all types of tuyere failure; however, the collective reasons for failure are excessive coal fines (–6·3 mm) and small mean particle size, low back pressure, blocking of tuyeres, scab formation and slip.

Surface Engineering of Low Rank Indian Coals by Starch-Based Additives for the Formulation of Concentrated Coal−Water Slurry

The rheological characteristics of three varieties of noncoking coals have been modulated by three starch-based additives, starch xanthate, starch xanthide, and starch phosphate. The apparent viscosity of the modified coal−water slurry has been measured by varying coal loading, additive percentage, pH, temperature, etc. Considerably stable concentrated coal−water slurry containing high weight fraction of coal could be achieved in each case, and slurry stays in a nonsettling form for 20−25 days with viscosity in a permissible low range. The effectiveness in reducing the apparent viscosity decreases in the order, starch xanthide > starch phosphate > starch xanthate. The plausible mechanism of slurry stabilization has been suggested considering the structural basis of an effective additive for the stabilization of coal−water slurry.

Water soluble graft copolymer (κ-carrageenan-g- N-vinyl formamide): Preparation, characterization and application

κ-Carrageenan-g- N-vinyl formamide was synthesized by free radical initiation using the potassium monopersulphate (PMS)/malonic acid redox pair in an inert atmosphere. The effects of variation of different reactant on grafting parameters have been studied by varying the concentration. Grafting ratio, add on and conversion showed an increasing trend on increasing the concentration of N-vinyl formamide, malonic acid, κ-carrageenan and the concentration of PMS from 6 × 10 −3 to 22 × 10 −3 mol dm −3. The optimum temperature and time for grafting of N-vinyl formamide onto κ-carrageenan was found to be 40 °C and 120 min, respectively. The metal ion sorption, swelling behaviour, flocculation and resistance to biodegradation properties have been studied. Flocculation capability of κ-carrageenan and κ-carrageenan-g- N-vinyl formamide for both coking and non-coking coals has been studied for the treatment of coal mine waste water. The graft copolymer was characterized by FT-IR spectroscopy and thermogravimetric analysis.

Modelling of Coal Pyrolysis Using a Twin Screw Reactor

Based on the balance equations of mass, partial mass, momentum and thermal energy, the pyrolysis process of non-coking coals using a counter-rotating twin screw reactor (TSR) is modelled by means of commercial CFD code PhoenicsTM . In favour of good convergence of the mathematical solution, a structured, cylindrical-polar grid is chosen. Variable filling and intermeshing degrees are taken into account by blocking numerical cells in gas domain and intermeshing domain instead of performing two-phase calculations in a body-fitted co-ordinate system. Viscous behaviour of the granular coals is expressed by means of a generalised Newtonian fluid and chemical decomposition is implemented with aid of distributed activation energies.

Prediction of Metallurgical Coke Strength from the Petrographic Composition of Coal Blends

Turkey, especially Zonguldak on the West Coast of Black Sea region, has large reserves of bituminous coal that can be used either directly or in blends with other coals for metallurgical coke production. It is possible to predict the coking properties of these coals by petrographic analysis. In this study, semi- and non-coking coals were blended with coking bituminous coals in varying proportions and an estimation was made as to their stability factors through petrographic techniques. It was established that semi- and non-coking bituminous coals could be used in the production of metallurgical coke.

Pilot-Scale Baum Jig Washing for Beneficiation of a High-Ash Indian Noncoking Coal

Coal will continue to play an important role in overall energy scenario in India. Despite its high-ash content, the run-of-mine (ROM) Indian coals are used directly for thermal power generation. There is an urgent need to improve quality of coal by reducing ash so that a consistent supply of quality coal can be supplied to the power plants. Pilot-scale studies were conducted on beneficiation of High Ash Indian Non Coking Coal obtained from the Samleshwari mines using a 20-t/h Baum Jig Washer. The results of the pilot-scale studies revealed that the ROM coal, containing 50% ash content, could be cleaned with the Baum jig providing a clean coal containing 36% ash at a yield of 52%.

Study on a multifunctional energy system producing coking heat, methanol and electricity

A multifunctional energy system (MES) capable of consuming coke oven gas (COG) and coal, and simultaneously producing coking heat, methanol and electricity, was subject to an exergy analyses based on Energy Utilization Diagrams (EUDs). In this system a coal-fired coke oven is adopted to produce coke and COG, where non-coking coal is burned to supply thermal energy to the coking process. The COG and coal gas gasified from coal in a gasifier, were mixed to produce syngas for methanol synthesis. Since COG rich in hydrogen and coal gas rich in CO, the mixture of COG and coal gas can easily adjust the mole ratio of CO to H 2 of syngas instead of the conversional reforming and shift processes. The active component of syngas is firstly converted into methanol and then the rest is introduced to a gas turbine for power generation. As a result, the overall efficiency of the MES system is about 62.3%, and its energy savings ratio is about 15% comparing with individual systems. The paper provides a new approach to use coal more efficiently and cleanly.