Ore-coal Pellets Research Articles

Technology Production of Ore Coal Pellets from Converter-Coal Slag Mix and Reduction Smelting of Steel

Technology Production of Ore Coal Pellets from Converter-Coal Slag Mix and Reduction Smelting of Steel

Steel Production from Metal-Bearing Waste

Analysis of two-stage iron and steel production by means of a blast furnace and an oxygen converter reveals its advantages and disadvantages. The main disadvantage is that carburization and decarburization of the metal are opposing processes and generate large quantities of waste with relatively high iron content. The organization of reduction and smelting of such waste—for the example of converter sludge—shows that direct reduction of iron by solid carbon, without carburization, is possible. Ore–coal pellets are produced experimentally. Their subsequent reduction and smelting yields metal ingots with the composition of steel.

A systematic approach to development of a technology of reducing smelting of steel

Dominating at present technology of steel production, comprising preliminary hot metal smelting following its oxidizing refinement, has considerable drawbacks and contradictions because of carbon overconsumption, losses of natural alloying elements, as well as formation of large amount of discharge gases and dust. Therefore, studies in the area of creation of alternative technology of reducing steel smelting are very actual. Presented theoretical statements based on comparative new views on direct reduction of metals by carbon according to donoracceptor mechanism. Their practical application allowed to elaborate a methodic of forming ore-coal pellets made of fine oxide concentrates and carbon-containing reducing agent in stoichiometric mass proportions for specified degree of metals reduction. Fusion of preliminary reduced pellets excludes excessive carburization of iron and provides production of naturally alloyed steel which does not require deoxidation and degassing. The ability to implement the developed technology is proven by results of experiments, which comprised metallization following by reducing smelting of ore-coal pellets, prepared of three types of concentrates with additives of charcoal and lime in calculated proportions. A comparative analysis of traditional and proposed technologies of steel production made. It was shown, that the developed technology of reducing steel smelting provides an effective processing of complex iron ore raw materials.

Reduction melting of metal-containing industrial wastes without carburizing of metal alloy

Metallurgical processing of group iron-manganese-chromium-containing raw materials and the production of steel and alloys are the fundamental basis of the industry. At the same time, they represent a significant part of the gas emissions into the atmosphere and solid waste accumulated in dumps. The traditional technology for the production of steel and alloys is based on the use of agglomerated raw materials, as a result of the preparation and processing of which the formation and accumulation of small and metal-containing waste takes place. For today, effective processing of them remains the problem of metallurgical sector. The present work is devoted to solving this problem on the basis of accumulated metal-containing waste of metallurgical and mining enterprises. Experimental studies on the preparation of ore-coal pellets from waste, their metallization and reduction melting in laboratory installations were performed. Based on the analysis of the results of experimental studies, a technology for reducing smelting of metal-containing waste has been developed. It is shown that as a result of the technology implementation, high-quality steels and alloys without carburizing of metal can be obtained, bypassing the stages of production of cast iron and high-carbon alloys. The experimental research method consists in preparation of dispersed metal-containing and carbon-containing industrial wastes of ore-coal mixtures with stoichiometric consumption of coal for recovering recoverable metals, and the obtaining of ore-pellets that are further subjected to metallization and reduction melting. As a result of the implementation of the proposed technology, samples of manganese-containing alloy steels with a carbon content in the range 0,44-0,52%, manganese 3,5-7,2%, and chromium-containing alloy steels with a carbon content in the range 0,42-0,46%, chromium 4,45-9,27% were received.

Manufacturing and Application of Metalized Ore-Coal Pellets in Synthetic Pig Iron Smelting

The article presents research data on manufacturing and application of metalized ore-coal pellets in synthetic pig iron smelting. A technology of pellets metallization by means of solid-phase reduction of iron from oxides using hematite-magnetite iron ore and low-caking coal as raw materials is described. Industrial testing of replacing 10, 15, and 20% of waste metal by the metalized ore-coal pellets in the coreless induction furnace IST-1 is described. Optimal temperature and time conditions of feeding the metalized pellets into the furnace in smelting pig iron of SCh-40-60 grade are determined.

Effect of iron ore-coal pellets during reduction with hydrogen and carbon monoxide

In this study, the effects of process parameters, such as gas composition and reduction temperature, were investigated. X-ray diffraction and scanning electron microscope were used to identify the products in different atmospheres. Experimental results indicate that the three-dimensional diffusion controlled model is suited to the reduction process. The compressive strength of the produced pellets gradually decreased as the temperature increased from 700°C to 900°C in all atmospheres. The formation of the iron whiskers made the adjacent grains loose and eventually caused the decrease of the compressive strength. The presence of H2 atmosphere had a strong effect on the pellets reduction due to the formation of porous and fibrous iron.

Study of the High-Temperature Reduction of Ore-Coal Extrusion Briquettes (Brex)

The technology of stiff vacuum extrusion, invented by the company J. C. Steele & Sons, has been put to use in agglomerating iron-ore concentrate and fine coal. The extrusion products (brex) were subjected to high-temperature reduction. This article presents results from modeling the behavior of brex under conditions similar to the conditions that exist in the ITmk3® process. It is shown that ore-coal brex can serve as an alternative to the ore-coal pellets used for high-temperature reduction in rotary hearth furnaces.

Mechanism of Reduction in an Oxygen Reactor for Ore–Coal Pellets Prepared with Low-Grade Manganese Ore

Mechanism of Reduction in an Oxygen Reactor for Ore–Coal Pellets Prepared with Low-Grade Manganese Ore

Aspects of the High-Temperature Reduction of Manganese Ores by Coal

The existing technology for producing ferroalloys based on manganese is quite energy-intensive and entails relatively large losses of the main element. The use of ore-coal briquets makes it possible to speed up the reduction of manganese oxides and improve on the performance characteristics of traditional ferroalloy production methods [1]. Ore-coal briquets or pellets are particularly effective if used in a new type of process unit ‐ the oxygen reactor developed by the Moscow State Institute of Steel and Alloys [2]. The technology involves the introduction of a charge containing ore-based materials, fluxes, and a carbon fuel, injecting oxygen or air into the fuel column through lances located in the lower part of the reactor, and injecting gas with an oxygen content in the range 5‐95% through top (auxiliary) lances located above the stockline. The ore-based materials are charged in agglomerated or pulverized form. Coke and/or coal is used as the carbon-bearing fuel. The main feature of the process is complete use of the calorific value of the coal and coke inside the reactor as a result of combustion of carbon monoxide above the column of carbon-bearing solid material. In addition, the use of green ore-coal pellets causes the reduction zone to be localized mainly on the surface of the coke column ‐ in the space where most of the heat used in the process is concentrated. The technology reduces the total consumption of carbon-bearing fuel, allows much of the coke to be replaced by coal in the green ore-coal pellets or briquets, and speeds up the smelting of pig iron and ferroalloys. The consumption of carbon fuel is as follows: for smelting pig iron ‐ 500 kg/ton (coke ‐ 200 kg/ton, coal in the briquets ‐ 300 kg/ton), instead of 600 kg of coke per ton of pig iron in blast furnaces; in the production of ferroalloys based on manganese, chromium, or silicon ‐ roughly 700 kg/ton (coke ‐ 300 kg/ton, coal in the briquets ‐ 400 kg/ton), instead of 2000 kg/ton in blast furnaces. Unlike blast furnaces, the reactor has no shaft, stoves, or complex charging equipment. This article reports the results of our determination of the optimum conditions for the rapid and complete reduction of manganese ores by coal under smelting conditions in the oxygen reactor in order to obtain carbon-bearing ferromanganese and silicomanganese. We studied the reduction of different manganese ores: oxide and carbonate Polynochnyi ores (Russia); Zhairemsk ore (Kazakhstan); Groote Eyland (Australia); Comilog (Gabon); Wessels High Grade (South Africa). The reducing agent used was gas coal of grade G containing 10‐15% ash and 15‐20% volatile matter (Table 1). The amount of reducing agent (carbon) needed was determined on the basis of the criterion of achieving complete reduction of the oxides of iron and manganese (Fe 3 O 4 and Mn 3 O 4 ). A prepared mixture with a mass of 2‐3 g was placed in an alundum crucible, covered with a tungsten cover, and lowered into a graphite-heater-equipped furnace that had been preheated to the test temperature (1600°C). The mixture was kept in the furnace for 3‐7 min. We measured the amount of mass lost by the specimen as a function of time under isothermal conditions. The degree of reduction of the charge was calculated as follows: α = {[(16/28)⌉M]/(M 0 Fe + M 0 Mn )}·100, %,

98/02335 Method for measurement of reduction degree in iron ore-coal pellets : Sun, J. et al. Gangtie Yanjiu Xuebao, 1997, 9, (4), 56–59. (In Chinese)

98/02335 Method for measurement of reduction degree in iron ore-coal pellets : Sun, J. et al. Gangtie Yanjiu Xuebao, 1997, 9, (4), 56–59. (In Chinese)

Production and use of pellets with residual content of carbon in blast furnaces

A technology for firing ore-coal pellets or briquettes in a neutral or reducing atmosphere has been developed in order to obtain pellets with a wustite-magnetite structure. However, the accompanying technological difficulties prevented its implementation on an industrial scale. In parallel with this work, a technology for firing orecoal pellets on conveyer firing machines in a reducing medium was tested. The essence of the new technology consists in combining elements of the technologies for pellets and sinter, i.e., preparing ore-coal pellets 15 20 mm in size and firing them by the method of sintering with air suction. Under specified conditions of the process of sintering of granules containing 4 6 % carbon (preliminary drying, ignition at

Development of Firing Schedule to Prepare Composite Pre-reduced (CPR) Pellets.

The newly developed CPR (composite pre-reduced) pellet, consists of a metallised sponge iron core encased in a partially reduced and sintered iron oxide shell. Such CPR pellets are obtained by firing a composite iron ore-coal char pellet prepared by two stage pelletisation. Iron ore and coal char mixed in desired proportion are pelletised to form core pellet which is further coated with iron ore only during second stage pelletisation. Such CPR pellets being developed mainly to utilise plant waste for preparing a cheap metallised feed for use in blast furnace. When composite iron ore-coal pellets are fired in air, CO(g) generated in core reduces not only iron oxide in-situ but also the outer shell partially. The continued firing reoxidised the reduced pellet unwillingly. The present paper gives a basic study of firing time and temperature to study the reduction behaviour of composite pellets followed by microstructural examination of fired and reduced pellets. The firing schedule, thus, developed was tested to prepare bulk quantity of CPR pellets having 28.6% metallic iron, out of total 76.6% Fe in the pellet rendering nearly 48% overall reduction degree together with sufficient strength (120±20 kg) which may enable its use as blast furnace feed.

Kinetics of reduction of iron ore—coal pellets

Kinetic data on the reduction of iron ore-coal pellets are compared with similar data for lump ore. It is shown that, when ore and coal are mixed intimately, the reduction reactions are accelerated considerably. Ore-coal pellets offer some additional advantages, as discussed in the text. It is shown that the kinetics of ore-coal reduction can be studied by using a pseudo kinetic parameter,f (fraction of reaction), defined as the instantaneous weight loss divided by the maximum possible weight loss. Plots off versust have been analysed to establish the kinetic equations and evaluate the kinetic parameters.