Many years of experience in laboratory petrography at the Eastern Refractory Institute have shown that the method of production of inorganic materials (parts) represents a deliberate change in mineral (phase) composition and structure of the original components to obtain the optimum composition of properties of the finished products. In connection with this, the main production parameters must be based on the prediction petrographic data.This article considers petrochemical aspects of the production of forsterite-spinel refractories from carbon ferrochrome slags. The use of the lattermakes it possible to significantly broaden the raw material base of forsterite-spinel refractories, thereby having reduced the significant shortage of magnesia raw material, and to provide a change in the production of carbon ferrochrome to a waste-free method. In dddition, forsterite-spinel refractories from these slags may be used as possible replacements for scarce and expensive magnesia-spinellide parts,The object of the investigation was the waste carbon ferrochrome slags of Serov Ferroalloy Plant and Chelyabinsk Electrometallurgical Combine. The slags are a byproduct of carbothermal reduction of Kempirsaisk chromite ore. Pervoural and Bakal quartzites are used as the fluxing addition and the reducing agent is carbon (coke).During electric arc melting in the ore melting furnace chromium and iron are reduced to ferrochrome and the difficult to reduce oxides of the charge are converted to a refractory magnesia-aluminosilicate slag.The results of investigations of carbon ferrochrome slags at the Chelyabinsk Electrometallurgical Combine [i] showed the presence in their composition of forsterite, merwinite, melilite, and chromespinellide, The increased merwinite and melilite content in the slags, caused by the addition to the charge of lime, significantly reduced their refractoriness and practically eliminated the use of them as a refractory material.It has been noted [2] that alumina has a negative influence on the properties of forsterite refractories since spinel forms low-melting eutecticswith forsterite. However, both in the USSR and abroad there are data on the production of forsterite-spinel refractory materials and parts from the slags of carbon and foundry ferrochrome* [3][4][5][6][7][8]. The possibility has also been shown of the use of foundry and carbon ferrochrome slag as a filler for heat resistant concretes [9][10][11]. However, the slag filler had insufficiently high thermomechanical properties as the result of the significant (up to 55%) content of comparatively low-melting glassy phase.At present in connection with the shortage of magnesia materials there has been a sharp increase in interest in investigation and utilization of forsterite-spinel slags [12][13][14][15][16][17] but the mineral composition of the ferroalloy slags has been insufficiently studied. The quantity of periclase added to them to increase the refractory properties of the parts has not been based on the actual phase and chemical compositions of...

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Magnesia-silicate rocks of different portions of chromite ores of Kempirsaisk massif in service at present are suitable for production of refractories [1][2][3][4]. We have investigated the properties of the dunite-serpentinite rock of the newly explored Poiskovoe chromite deposit of the Kempirsaisk region for the purpose of establishing of the possibility of use of it as a raw material for production of forsterite refractories and the development of a no-waste method of processing of chromite ores. A bulk sample of dunite-serpentinite rock taken from the core of a bore hole in detailed exploration of the deposit was investigated.The rock consisted of apodunite serpentinite (42%),* serpentinized dunite (17.5%), dunite (22.0%), peridotite (12.5%), and dunite-peridotite (6%).The chemical compositions of?the varieties of dunite rock are shown in Table i. All of the varieties of the investigated rock are stable in chemical composition and similar to Solov'evogorsk dunite, which is used for production of magnesia-silicate refractories.However, in comparison with Solov'evogorsk dunite, the investigated varieties are characterized by increased weight quantities of CaO (from 0.43 to 0.70%) and SiO 2 (from 35.10 to 36.8%).The increased SiO 2 content in the investigated rock leads to a decrease in the silicate modulus and some reduction in the refractoriness of the material.The refractoriness of the varieties of rock varies from 1670 to 1710~ and the refractoriness of the average sample is 1700~On the derivatogram of the dunite-serpentinite rock (Fig. I) there are observed three endothermal effects, at ii0, 400, and 700~ and two exothermal, at 810 and I160~ The endothermal effect at II0~ corresponds to removal of the adsorbed water and the effect at 400~ is caused by dehydration of brucite (about i0 wt.% brucite in the sample).The very intense endothermal effect at 700~ is caused by failure of the serpentine lattice in removal of the constitution water (up to 9%) and formation of amorphous metaserpentine as a new primary phase.The exothermal effect at 810~ is caused by rearrangement of the structure of metaserpentine and decomposition of it into forsterite and clinoenstatite:3MgO.2SiO~ ~2MgO'SiO2+MgO.Si02.The form of the endothermal effect on the DTA curve and the simultaneous loss of weight occurring as a jump on the DTG curve apparently makes it possible to consider this form of serpentine as a material with a defective structure.On the basis of thermogravimetric analysis it may be concluded that in decomposition of serpentine x-ray-amorphous phases of forsterite and enstatite are formed with subsequent crystallization of them (exothermal effect at I160~The above described endothermal and exothermal effects are characteristic of Solov'evogorsk dunlte'. *Here and subsequently wt.% is shown for chemical composition and vol.% for phase. tYu. E. Kuperman, Phase and Structure Transformations of Solov'

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