Corundum Smelting Solutions
Corundum smelting production process, raw material selection and the source of the quality control is a process is necessary to strictly control crucial; the selection of raw materials determines the scope of application of its products to a certain extent; the quality of the raw materials can be effectively controlled, not only affect the quality of products and service performance seriously at the same time, but also directly affect the manufacturing cost of corundum production; therefore, the corundum production process must be strict control of the main raw material of iron, bauxite, anthracite, especially the amount involved on Si02, Ca0 should strictly control the raw materials. To Si02, Ca0, not only to the production difficulties, affecting the manufacturing cost, reduce the price of L203, Ti02 element content, but also because of the lack of quality affects the application range of the product prices of commodities and products.
Si02 as a glass substrate, too much into the corundum matrix makes the toughness and hardness index significantly decreased seriously affect the use of corundum, corundum abrasive performance; but Si02 and AL203 generate a small miscible phase, mullite (3 AL203.2 Si02) state of uniform dispersion in alpha - AL203 grain boundary so, for the self sharpening abrasive is beneficial, the content of Si02 in brown corundum, requiring less than 1%. Ca0 restrictions on the crystallization of corundum is not, as long as the content of Ca0 was less than 8%, in brown corundum smelting process in the first crystallization phase for corundum, experiments show that the Ca0 content reaches 3%, the CA6 will generate corundum (six calcium aluminate), excessive. It will not only make the corundum micro declined significantly hardness, calcium aluminate low melting material produced by (C3A, CA, the melting point of 1360 DEG C) will seriously affect the thermal properties of corundum material, which is very harmful, for use as a refractory corundum so as refractory corundum Ca0 content must be less than 0.5%, and as a high-quality refractory material for small Ca0 content 0.3%. [in the raw materials of Fe203 in smelting corundum as valuable elements included; Ti02 is the main component of corundum coloring, but also promote the increase of microcrystalline corundum and corundum ceramics toughness; accelerator Mg0 is microcrystalline corundum, the amount of Mg0 (the melting point of 2800 DEG C) to enter, can improve the toughness of corundum, synthetic the performance of corundum will improve]. By using the above principle, we can design and produce different kinds of corundum.
The causes of high silicon, calcium alumina raw material analysis of bauxite corundum smelting bauxite clinker and the production of metal aluminum and refractory raw materials with different bauxite, corundum smelting bauxite is used in high-quality high AL203, low Si02, Ti02 Ca0, and the production of aluminum and alumina refractory with the above requirements of raw materials is relatively low, it can meet the needs of production.
The production of bauxite corundum with harmful impurities in SiO2, CaO is a source of bauxite in the consolidated material itself; two is to face with fine soil mixed with bauxite. The former is the raw material itself contains, can control the discretion in the choice of raw materials, or ore processing to ensure the quality of raw materials selection, and the latter is more important source of involvement, which requires the Corundum manufacturing enterprises themselves to strictly control. The bauxite resource is becoming increasingly scarce, the fine soil surface mixed with bauxite in May will be more serious, which makes the production enterprises in the "and abandon, but can not use" dilemma, but it also brings serious difficulties and challenges to Corundum manufacturing enterprises. In addition, from the above analysis, mathematical materials, anthracite iron harmful impurities in SiO2, CaO should also pay enough attention to and strictly control the cause. Because the SiO2 and CaO mixed with excess leads to the rising cost of manufacturing, corundum production enterprises consume electricity and raw material, more important is the quality of products out of control and performance constraints, find solutions to both economic and reasonable imperative.
Process design and control
SiO2 and CaO are very harmful to the product quality and the application range of the brown corundum. In the corundum smelting process, SiO2 can generate low silicon iron removed by gasification of sublimation or reduction, and the CaO is very difficult to get rid of the corundum smelting process, so it is necessary to strictly control the raw materials (bauxite, anthracite, iron) in CaO intake, and designed the technology scheme reasonable and adapt to with the shunt and control of its target.
A) recovery and utilization of high SiO2, CaO powder 1, material recovery through mathematical analysis, excessive alumina mixed powder into inferior charge is caused by raw material SiO2, CaO seriously exceed the standard of one of the main reasons, therefore, this part of the inferior mixed powder for dispelling or effectively control the amount is very necessary the. By collecting or screening treatment can reach inferior powder and bauxite separation purposes. Separate the high SiO2, CaO separate storage, and use it for another. 2, powder pellet processing material for smelting process can be carried out smoothly, must ensure that the burden of a certain size, in order to achieve the ideal gas charge effect in smelting process. The recycled powder for pellet processing, can achieve the purpose of smelting materials, at the same time in the pellet processing with compound additives to ensure proper smelting process, the quality of corundum achieve reasonable control target. 1) prepared simple assembling and easy maintenance, the drum type mixing machine and pellet molding machine; 2) drying heat Outsourcee selection of corundum comprehensive utilization of heat energy; 3) pellet conveying by three-dimensional climbing car. 3, the selection principle of compound additives 1) technology is feasible, no bad effects, does not affect the corundum product quality; 2) simple, rich resources for security; 3) economic and reasonable, is conducive to the target cost control; 4) high consolidation strength, no influence on the environment; 5) to raise the smelting efficiency, simple operation.
B) process control 1, to prepare for the purchase of raw materials for classification control, so that the source controlled. The SiO2 of the main raw material for smelting brown corundum, under normal circumstances is generally controlled within the range of less than 6%, while CaO should be controlled within the range of less than 0.5%. 2, has purchased the fine soil entrained in the face of bauxite (screening or dust recovery) pretreatment, in order to ensure the stability of purification and smelting of raw materials. 3, strict control of anthracite (Jiao Tan) and impurity content of iron, the amount of involvement from the source control of coal gangue, casting sand and other impurities, ensure the production of raw materials in a controlled state. 4, not only the bauxite, anthracite, iron in the ingredients before strict picking, but also on the main raw material into the furnace bauxite chemical composition and particle size of reasonable design and strict control, we design a reasonable proportion of the early, middle and late smelting materials, and strictly control the size range of raw materials, to to ensure the smooth process of smelting. With reasonable design, using 5 of recycled fine powder, in the smelting process, according to the principle of corundum smelting, melt adjust the pH in proportion into the reducing agent, clarifying agent, fluxing agent, accelerant and other raw materials, through processing into spherical or composite materials must block, re smelting this is not only better, comprehensive benefits, reasonable economy, reducing smelting difficulty, more important is to realize in the smelting process of brown corundum quality control.
C) 1, the process design process: bauxite (anthracite, iron) prosecution, warehousing of raw materials preparation (grading control preparation, drying, pelletizing, proportioning, smelting), dumping, cooling, crushing separation, measurement and storage design, 2 smelting smelting technology is an important process, brown corundum production through proper control of smelting, smelting atmosphere, the bauxite and reductant (anthracite or coke), clarifying agent (iron) redox reaction, the removal of impurities in the condition of high temperature, and the formation of alpha - Al2O3, which conform to the quality requirements of the corundum block. 1) charge for target design, reasonable control for furnace materials; through the rational allocation of the furnace melt pH, optimize into charging design, so as to obtain good metallurgical indexes.
Through the analysis on body composition of dust, which at about 40% SiO2, Al2O3 in 40%, K2O in 10%, and the rest is Fe2O3 and toner. In the smelting process about 50%TiO2 was reduced, into the low Fe - Si alloy to elemental Ti, the rest of the TiO2 to the valuable components into corundum block, and alumina impurities in marketable MgO and CaO retained its inherent impurity content into corundum block. 3) burden ratio calculation: the raw materials to 1000kg bauxite: formula of corundum smelting anthracite: (SiO2% * 0.4 Fe2O3% * 0.225 TiO2% * 0.15 /C% * 1000kg=) formula of anthracite corundum smelting iron dosage (SiO2% * 0.467 * K-Fe2O3% * /Fe% * 0.7) 1000kg= type: SiO2%, iron dosage Fe2O3%, TiO2%%, Fe2O3 content in raw material SiO2 and TiO2 respectively, C%% of the fixed carbon content in anthracite, iron content of iron in Fe%, K is the iron silicon ratio (K value 5.5) 4) smelting cycle design according to the capacity of smelting equipment, design of charge batch preparation system, smelting charge points before, during and after respectively with charge difference is to solve the optimal process design, very useful for the technology and economic effect. In the early stage of smelting: in order to improve and ensure the temperature is not lost as the goal, to the mixture, is added into the 60 - 70% of the total charge for good. The smelting medium-term: to ensure the whole smelting process, smelting furnace gas medium must ensure that the effect is good, this is the most important link in the whole process of smelting furnace, only to ensure good ventilation effect, excessive SiO2 and SiO in the furnace exhaust gas to escape outside the furnace, in order to obtain satisfactory quality and good the technical and economic indicators, in order to get good control in the late period of smelting; was added into 30 - 20% of the total charge for good. In the later stage of smelting, the effective design of the material is very important in order to adjust the quality and increase the output. Because the charge into the refining stage, temperature control, shorten the smelting time is very important, this period is the key to the whole process of technological economy, the charge was added into the 5 - 10% of the total charge for good.
3, 1) before furnace smelting process control: adjustment in the production process, the user can according to the requirements of quality indicators, proper control of smelting reduction degree, effective control, to achieve the quality but because incoming bauxite and batch number and sampling method and operation method of smelting and other factors, in the actual production process sometimes, need to stick with the furnace through the pre judgement adjustment (to be familiar with the operation process of formulation and process, can be cancelled before furnace adjustment). 2) reduction furnace control: due to increased Al2O3 content in bauxite decreased and the content of SiO2 in the smelting process, it is necessary to increase the amount of C involvement, which makes the reduction furnace atmosphere agglomeration strengthened, produce high temperature gases, thereby increasing the smelting operation and furnace control in C and increase the difficulty; the amount of Fe case, the SiO2 can effectively get rid of, but because of the reduction of TiO2 in minerals and other valuable components are a reduction in metal Ti form into the low silicon iron, the quality and performance of corundum decreased, application field is limited, therefore, an appropriate arc discharge. Let SiO2 and SiO emissions effectively is necessary to escape. 3) smelting parameters control: in order to get good technical and economic indicators, the smelting process technology to adjust the necessary changes with the degree of material, according to the pool, current and voltage adjusting the smelting process, is the necessary control methods and means.
4, the smelting process control and operation skills are the main smelting process, corundum production by smelting, the bauxite and reducing agent, clarifying agent of redox reaction, the removal of impurities in high temperature, and the formation of alpha - Al2O3, which conform to the quality requirements of the corundum block. For the high SiO2 and CaO content of bauxite, the analysis from the aspects of theory and practice, whether it is brown corundum smelting furnace or fixed furnace dumping its smelting process is different from the traditional. 1) arc: technically feasible and economically reasonable carbon arc block by arc, without or with as little as possible with iron, so safe and economical, the arc cost savings of around 50%; 2) ingredients: pre smelting stage (first batch) feeding based on relatively normal ingredients add less iron, in the middle and late one by one with the required amount of iron, so that you can get a better technical and economic effect; 3) charge control: pre smelting by thickness of the material combination into charging system, stew furnace smelting, to reduce the loss of furnace temperature; the mid air block of pellets. The SiO and SiO2 steam smoothly from the furnace to escape, so as to ensure the stability of furnace, saving iron dosage and the increase of smelting rate; the middle open arc after deflation, the late addition should be to consider appropriate burden by some fine, in order to ensure the rapid melting furnace , reduce heat loss and improve the smelting rate; refining period using high-quality bauxite powder or brown powder, soft cover insulation technology, improve production quality, to ensure that the furnace; 4) smelting parameters of molten pool and reasonable arrangement: in the furnace under the condition of considering the safety production and improve the yield point of pre smelting furnace. (relative) easy to use the high voltage and low current (fixed furnace is more reasonable), so beneficial to expand the pool of furnace area, which is safe and can increase the yield of smelting, the effect will be better; smelting furnace should be adjusted according to the middle power (current, voltage), to ensure that the burden of escaping gas smelting, smooth; smelting later to effectively increase power delivery, to refining period is particularly important, at the same time with high quality powder smelting economic indicators will be better. 5) open arc gas for high SiO2 and low Al2O3 bauxite smelting, increasing reductant mixing times and the amount of time and the open arc gas, more conducive to the furnace SiO, SiO2 steam successfully escape, so not only can remove harmful impurities and save iron adding capacity. It is good for the quality of the products.
The design of high silicon smelting process, calcium burden:
Smelting scheme: non separate smelting. Technical scheme (omitted) two smelting scheme: single fused brown corundum. Process plan (omitted) three (): according to the chemical components of the material, to determine the production of other corundum or special products (SiO21.2 - 1.5), the technical scheme should be designed separately.