| In this dissertation, in meet the needs of low costs and environment protection for metallurgical process, the key technique of carbonization of brown coal is solved, and the system, named the LV automatic intelligent-compensation injection system, for the novel solid reductant is developed on the basis of manually operated equipment. The reductant, which is made of brown coal, is successfully used in copper pyro-refining process instead of traditional reductants, such as wood, charcoal, heavy oil, LPG, natural gas, ammonia and propane. The system is successfully applied to the processes in Jinchuan Nonferrous Metals Co.(Group), Gansu Province and Yunnan Copper Co.(Ltd), Yunnan Province, and the problems existed in metallurgical operation and engineering suitability while using the reductant are solved.In study of comprehensive utilization of brown coal, the reductant production and the gas which is used as energy resource are researched. The possibility of other crackates used as chemical raw materials(e.g. for production of methyl alcohol and dimethyl ether) is discussed. Due to this study being designed to producing novel reductant used in metallurgy, the high value product can be obtained and the good economic performance can be reached. It also provides a new train of sought for exploiting brown coal resource. The semicoke from brown coal has an applying prospect in blast injection, phosphorous production and carbide production besides in high temperature electro-metallurgy and nonferrous metallurgy.The experimental results show that the quality of semicoke is:fixed carbon> 72%, volatile ca.12%, ash< 16% and specific resistance> 4000Ω·mm2/m under the carbonization condition of indirect heating temperature of 800℃for 1 h when use of brown coal from Mile County, Yunnan Province. The quality meets the needs of reductant for copper pyro-metallurgy and for ferroalloy production.The characteristics of brown coal carbonization is thoroughly considered in designing the equipment in industrial scale experiment. Firstly, the semicoke product is non-coherent because of its bad coking characteristic, and the ramming machine at side door of the furnace is not suitable. Secondly, the carbonization furnace is designed as shaft one which can be operated continuously with feed inlet at the upper of the furnace and products outlet at the lower of the furnace. Thirdly, the brown coal and semicoke are chemically active and may be burned with oxygen in air which can be resulting in lowering of the fixed carbon in semicoke. Fourthly, a large amount of CO and hydrocarbons exist in furnace gas. Therefore, the carbonization furnace with external heating is designed, and it has the advantages of fast carbonization, avoid of burning loss and autothermal process. Those can be expressed as follows:(1) Different kinds of bricks are used in different parts of the furnace to lower the cost and guarantee furnace life. The carbonization chamber is masonry work of silicon carbide bricks which have the excellent heat conductivity; the combustion chamber is masonry work of silica bricks; and of the furnace the drying nest and the cooling zone, in which it is with low temperature but the temperature changes fast from time to time, are masonry work of firebricks. (2) To keep the wall of carbonization chamber heating evenly, the furnace gas is conducted from the inlet at the upper part of burning chamber, then it is burned downward, and the flue is removed from the outlet at the lower part of burning chamber. (3) A great amount of furnace gas generate in pyrolysis because of 12%(Ad) of tar content in Mile brown coal. The measure for comprehensive utility is that the volatile gas from pyrolysis process is conducted to purification system first. Then the gas with high temperature is cooled in No.1 heat exchanger, in which tar vapor is transformed from gas state to liquid state. The steam in raw gas is transformed to liquid water in No.2 heat exchanger and the calorific value of gas is increased. Finally the gas is used as fuel in the burning chamber of carbonization furnace. The temperature adjustment of flue in No.1 heat exchanger is controlled with air flow.The key factor to guarantee stable and smooth carbonization process is water content in brown coal. The main problems caused by high strength of water in the coal are the decreasing temperature in carbonization chamber because of heat absorption brought about by water evaporation, the lowering of furnace productivity because of the longer retention time of charge in furnace, the low strength of gas in flue because of less amount of charges in unit time, and the difficulty of autogenesis balance because of less amount of gas in burning chamber. So the following is the drying method designed by this study:The several squirrel cages, made from reinforcing bars, are placed side by side and kept suitable distance on the drying chamber ground. The one end of the cage is connected with main blast line. After brown coal is put in cages, the air at normal temperature is blown from main blast line and the coal can be dried to 25% of water in content. Then the hot air is blown from main blast line in which the flow from heating exchange chamber is changed and it can be dried to less 15% of water. To reach the overall drying effect, the key is to make the saturated wet air in brown coal charges flow and escaped out of charges. This is proved by actual production process. Even if the ordinary air is blasted, the drying is not slow. The decrepitation happens in drying process and fines produces. But flow paths are unlikely blocked. The mechanical distribution and discharge may be realized in this design, and it is in low investment, low running cost and suitable for industry.The experimental results of developing reductant from brown coal for silicon production show that the refined semicoke in which the ash content is less 4% can be obtained when brown coal is de-ashed carefully by coacervation with oil and selective flocculating. The main factors that influence the de-ashing process are:(1) The particle size affects de-ashing process by coacervation with oil considerably. The cleavage of minerals and inorganic substances needs semicoke particles ground to-250 mesh. (2) Low strength of pulps is beneficial to flocculating. (3) The use level of flocculant has a key effect in flocculating process on de-ashing. The best level is 30%-40%, and under this condition the formed conglomerate is the densest and the recovery of semicoke is the best. (4) In the process highly agitated, the de-ashing effect is favorable when the agitating strength is 12000 r.p.m. and coacervating time is kept in 10 min. (5) The de-ashing effect also is influenced by the way of putting in flocculant oil. The better effect can be achieved when the emulsion is added in the pulps after a suitable amount of diesel oil and water are emulsified. It is also beneficial when the pulps is added with dispersion agent. (6) The semicoke from brown coal is with high porosity(as activated carbon), the ash particles in pores are difficult to remove and this results in being hard to de-ash thoroughly.Iron, calcium, magnesium and aluminum in ash of semicoke can be removed by hydrochloric acid. The leaching vessel is designed as the inlet at bottom and the outlet at top. Under the leaching condition of semicoke particles<0.5 mm, liquid solid ratio 2:1, HCl strength 2 mL/L and leaching time 16 h at normal temperature, the ash content in semicoke after leaching are 9.37%, and main compositions of the ash are SiO281.09%, Al2O313.36%, CaO 0.74%, Fe2O31.87%, MgO 0.20% and Fe 0.18%.The harmful impurities in semicoke can be removed by coacervation with oil or by chemical leaching, and the quality of refined semicoke can meet the requirement of reductant used in silicon industry. Both methods have advantages and disadvantages. The difficultly of coacervation with oil is flocculant oil should be recovered by indirect heating and the equipments are complicated. Chemical leaching is with the advantage of simple process and equipment, but Cl- ions in products might be potentially harmful to metallurgical process.The development of LV automatic compensation injection system is made the automatic reducing operation possible. The distant convey of redutant and injection are realized. The system is with the characteristics of automatic, high efficiency, safety, environmental protection and intense. It is composed from feeding unit, supporting and weighing unit, safety and anti-explosion unit, fluidizing and pressurizing unit, fluidizing and mixing-adjustment unit, feedback adjustment and jetting unit, pneumatic control unit and PLC control unit. It is an advanced, systematic equipment for carbonaceous reductant to replace high pollution reductant or high cost (e.g. heavy oil and LPG). It is with extensive adaptability and spreading values for reaction control of gas-liquid-solid system in bath smelting.The novel reductant and the automatic injection system are successfully applied to copper smelting shop in Jinchuan Nonferrous Metals Co.(Group). The reducing process is stable in 75t anode furnace of the smelter, and heavy oil used before is replaced by the reductant. The reducing time is 50～80 min, which is less 30 min when heavy oil is used. The surface of anode product is smooth. The blackness of flue from reducing process is grade 1 in Lingermann scale, and the problem of emitting black flue when heavy oil is used as reductant is solved. The unit consumption is 13～18 kg/t-Cu. This slightly higher consumption is caused by two reasons:one is highly oxidization of copper melts because there is a mount of nickel in it; the other is shadow bath of 75t anode furnace. The cost for every 10 thousand-ton anode can decrease￥906000 compared to heavy oil reductant. Actually, the most benefit is obtained by deceasing reducing time which decreases the operation cost, the cut down of energy resource cost is more than 10 million yuan every year.Research on anode from refining process in Jinchuan Nonferrous Metals Co.(Group) shows that in order to decrease oxygen content in anode several measures can be taken:In oxidizing process, it can be controlled according to nickel content in copper melts. Adding cold burden to copper melts can dilute the solution under the condition of high nickel content. And slag in oxidization process should be tapped as complete as possible. The adjustment of oxygen in anode is mainly in reducing process. Therefore sample taking and analysis in situ are necessary to determine reducing time and reductant injection.Research on de-nickel and its phase pattern control shows that nickel exists in the form of Ni-Cu alloy in copper melts and in CU2O which is dissolved in copper melts. NiO and other forms of nickel are not found yet. In pyro-refining process, especially in reducing operation, de-nickel is thermodynamically impossible. So, de-nickel is mainly completed in pure oxygen blowing operation in Kaldo furnace. In reducing operation, nickel can be kept in the slag because the novel reductant has an effect of adjustment for slag composition and nickel fixing to some extent. Thus the quality of anode is improved.The main new ideas of this dissertation include that in metallurgical process the novel reductant used in copper pyro-refining from brown coal is developed for replace of heavy oil, natural gas and charcoal, that in equipment carbonization furnace for producing semicoke from brown coal is designed and developed, and that the design and development of the LV automatic compensation injection system are based on the deep understanding of control of metallurgical process.In the process of research on novel reductant, novel equipment and applying it to copper industry, the key problems in metallurgical process and engineering are solved successfully, and the achievements in this dissertation are turned to realistic productive force.
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