The Study On Formulation Optimization And Mechanism For Using Chromium Slag To Smelt Special Ferrochrome

This paper summarized the production situation and waste disposal situation of calcium roasting process and non-calcium roasting process and introduced the production in the process during exploration and discovery from the first chemical industry in China who used non-calcium roasting process to product chromate. Because of the harmfulness of chromium slag, the treatment of non-calcium chromium slag has become one of the most important problems in the development of the factory.Although the factory has been accomplished scale industrialized production by using semi-coke reduction of chromium slag to produce calcium chromium cast iron.Because there is no professional smelting personnel involved in the process at the beginning,resulting in the presence of high power consumption, equipment failures and instability ingredients in post-smelting.In this paper, the physical and chemical properties of raw materials were determined by X fluorescence spectrum analysis, chemical analysis, XRD analysis and so on,the theoretical calculation results were verified and optimized by the small scale industrial simulation experiment.Finally,it is determined that using the pellets in the size of 6~10 mm made by 73.1 % chromium slag, 16.0 % semi-coke, 6.9 % silica and4.0 % vanadium slag in 40 V voltage to smelt can reach the best effect in the 80 KVA small single-phase furnace.In order to solve the problems in the process of smelting,in this paper, the basic reaction mechanism of smelting process is analyzed in the view of thermodynamics and kinetics,and the basic mechanism of smelting analyzed and examined by the meltingpoint test, Thermogravimetric analysis,Mineralographic microscope, X-ray diffraction and Scanning electron microscope-energy disruptive spectrometer. The results show that the reaction contacting near the reductant semi-coke is better in the process of smelting,the interfacial reaction is mainly the diffusion from C elements to the chromium slag and reducing metal from chromium slag, no new material producted at200℃、300℃ and the loss of water or some gases from the raw materials, a new phase composition of chromium and iron appeared gradually at 750℃, generating some Fe as simple substance at 900℃ and some Cr as simple substance at 1350℃,the existence of Fe elements changing as Fe2O3�'Fe3O4�'Fe O�'Fe with the increasing temperature,and Cr2O3 beginning reducing under the action and slagging elements.Finally,the following optimal scheme are put forward on the current process improvement program by studying the results: strictly controlling the feeding size in the range of 6~30mm, improving ball making technology to increasing the strength of the furnace pellet, optimal selection of reducing agent.