| Rich titanium material generally refers to the titanium slag, artificial rutile and natural rutile that TiO2content is not less than75%. The product smelt from the electric arc furnace is called as titanium slag (the product can be called as high titanium slag, if TiO2content in titanium slag is not less than90%). The products that TiO2content is not less than90%but produced by other methods, it is called as artificial rutile. Rich titanium material is the important raw materials for production of titanium dioxide and titanium sponge. Therefore in production, how to furtherconcentrates the ilmeniteto obtain rich titanium material with higher TiO2content, which is important for the development of titanium industry. In China, rich titanium material industrial production is mainly dominated by titanium slag, the reason is that the ilmenite is predominant in titanium resource, rutile is expensive and reserves less.The essence of titanium slag reduction smelting in electric furnace is to reduct Fe and enrich titanium. Ilmenite and solidreducing agent, anthracite or petroleum cokeare are fed into electric furnace after mixing, then reducing and smelting generally at1600～1800℃. The iron oxide in ilmenite can be selectively reducted to iron, and titanium oxide can be enriched in furnace slag, eventually titanium slag and by-product pigiron can be obtained through separation.Titanium slag has a high melting point (1580～1700℃), and the melt titanium slag has a very strong corrosion. Furthermore, with the temperature down close to melting point, its viscosity increases sharply, and the viscosity change significantly with the changing of titanium slag components, therfore,the safety requirements of titanium slag smelting in the electric furnace is very strict. This paper also analyzes the possible hazards during the process oftitanium slag smelting in the electricfurnace,such as high temperature, high voltage, slag foaming, and CO.Combining the80kt/a titanium slag factory of a company inYunnan to analyse hazards, and firstlythe titanium slag factory is divided into the following five units:(1) raw material preparation system;(2) the electric furnace reduction smelting system;(3) the molten iron and titanium slag processing system;(4) pig iron factory;(5)Slag processing factory. The (2),(3),(4) unitsare mainly taken as research object.There are many ways to identify hazards,such as safety inspection table method, the event tree analysis (ETA), fault tree analysis (FTA), the preliminary hazard analysis (PHA) are commonly used. This subject will adopt the preliminary hazard analysis method for analysis.Some common risk evaluation methods:risk assessment method, graham method. This subject mainly puts to use the graham method for evaluation.Evaluate with PHA,we can get:among hazards existing in the80kt/a titanium slag factory,the level of fire, explosion, poisoning and choking is highest, which all maybe causing casualties and damage to facilities and equipment. The level of other hazards takes second place. The hazards may occur in the electric furnace reduction smelting system, dedusting purification system, iron and titanium slag processing system are gas explosion, explosion when iron and titanium slag meet water, pressure vessel explosion; Dust explosion may occur in the raw material preparation system and electric furnace reduction smelting system; Fire main may occur in the area where CO is putout, the electrical equipment and electrical circuits; Poisoning and choking main may happen in electric furnace smelting system and dedusting purification system, in the later production the necessary precautions should be taken about those dangerous factor.Analyse with graham method,we can get:the degree of the electric furnace reduction smelting system and dedusting purification system is "serious risk", which should strengthen the management, mainly prevention. The molten iron and titanium slag processing system, electrical system is"moderate risk", which should take corresponding security measures. Other systems are relatively safe.For the above analysis,in the actual production of80kt/a titanium slag factory,the system of the production, operation, management and safety procedures should be further improved, to ensure production infallible;... |
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