SU398657A1 - В П Т Б •• '- ^ ft-OTrjn> & - (i-! I Uu - Google Patents

Description

one

The invention is based on the methods of producing metallic chromium and its alloys and can be used in the ferrous industry.

A known method of processing chrome ore by melting it with ferrochrome and lime and restoring the chromium lime melt.

However, in a known manner, it is impossible to obtain in the second stage (when chromo-limestone melt is reduced) a metal with a chromium content above 80-85% and iron below 15-20%.

The proposed method differs from the well-known fact that after the melting of the shnchta is non-reduced by reduction into the melt, a precipitator is set in the amount of 5-12% by weight of the melt, consisting of oxides and an active reducing agent.

This makes it possible to obtain an alloy with a chromium content of not less than 97% and iron not more than 1.5%.

The proposed method of drying is carried out in the following way.

After the complete melting of shih.khty consisting of ferrochrome, lime and chrome ore, before the melt is restored, a precipitator is introduced into it in the amount of 5-12% by weight of the melt. The precipitator is a mixture of oxides, for example chromium oxide or

iron-free chrome concentrate and active reducing agent, such as aluminum powder or crystalline silicon. Moreover, the ratio of components of the precipitator is calculated so that the resulting metal drop resulting from the oxidant and the reducing agent contains an excess of the latter. When the cannula is lowered through a layer of chromium-limestone, the iron oxides, phosphorus, and other impurities are reduced from this condition, this condition causes the canel to precipitate (coagulate) and precipitate them onto the sub-HN bath of the furnace. At the same time, the trouble lasts is cleared of the indications. Then, the solid skimmer is drained into a specially prepared ladle and restored with aluminum, silicon or other iron-free and carbon-free reducing agents, for example, iron-free silica-chromium.

The proposed method provides a metal with a chromium content of not less than 97%, iron not more than 1 -1.5%, phosphorus not more than 0.010%, nitrogen not more than 0.05%.

The cost of such chromium is 30–40% lower than the cost of metallic chromium, currently produced from metallurgical chromium oxide, and 20–30% lower than the cost of chromium from iron-free chromium concentrate.

Pfimer. In an electric arc furnace with a capacity of 750 kVa, a mixture was melted, consisting of 800 kg of chrome ore (51% chromium oxide, 12% ferrous oxide, 18% magnesium oxide, 8% alumina and 5.8% silicon dioxide), 800 kg carbon ferrochrome (70% chromium and 7-8% carbon) and 660 kg of lime (92% calcium oxide).

By melting the charge on the rasflav mirror, the disconnected furnace furnaces were injected with a precipitant consisting of 40 kg of chromium oxide and 40 kg of aluminum powder. Before the treatment with the precipitator, the melt contained 1.0–2% of iron and 32–38% of chromium oxide, after the introduction of the precipitator and some (5–6-minute) exposure, the iron content in the melter decreased to 0.2–0.5%, and chromium oxide was 28-33%.

Then the melt was poured into a ladle lined with magnesite, the weight of the melted melt was determined from the level of its filling and a reducing agent (a mixture of crystalline silicon and aluminum powder) was introduced. The resulting metal contained 97% chromium, up to 1.5% iron, 0.0017% phosphorus, up to 0.008% nitrogen, and less than 1% cream. The content of chromium oxide in the waste slag was in the range of 2-4%. Through a tap hole installed on the furnace's bottom bath, ferrochrome of composition 67% chromium, 0.04-0.05% phosphorus was released, the content of other impurities also met the requirements of the standard.

Subject invention

A method of processing chrome ore by proplavleia it with ferrochrome and lime and

recovery of a chromo-limestone melt, characterized in that, in order to produce an alloy with a chromium content of not less than 97% and iron not more than 1.5%, after melting the charge before being reduced, a precipitator is added to the melt in an amount of 5-12% by weight of the melt , s of oxides and active reductant.