From Table 1 below, we can see that the smelting slag system of antimony smelting furnace is FeO-SiO2-CaO ternary ig slag system. Since there is no specific research on refractory materials used in antimony smelting furnace in China, we can refer to the refractory materials used in smelting furnace with the same slag system for copper, lead and zinc for preliminary analysis.

Table 1 Average chemical composition of slag samples from a large antimony smelter in China

1, thermal stress damage

Although the temperature of antimony smelting is not high (1100~1200℃), the addition of cold material at the end of each furnace period (10 hours/furnace) will make the temperature in the furnace drop sharply, and there is a temperature fluctuation of about 300~400℃ in the furnace. The frequent temperature difference changes make the lining brick form a temperature gradient, and then produce a large thermal stress. Frequent thermal shock will continuously reduce the strength of the refractory. When the thermal stress is greater than the strength of the lining brick, the brick will crack and flake. Therefore, the refractory used in antimony smelting furnace has certain requirements for thermal shock stability.

In addition, in order to compress the construction and opening time, many refiners arbitrarily shorten the kiln time after overhaul, so the kiln should be heated strictly according to the temperature curve (for example, the furnace is a reverberatory furnace, and the pull rod at both ends of the reverberatory furnace should be gradually relaxed as the temperature rises, and the pressure should be adjusted to avoid greater stress due to the temperature rise). Avoid the phenomenon of spalling and cracking caused by large thermal stress caused by large temperature difference.

2, metal and sulfide erosion of refractory materials

During the use of refractory materials, the melt can penetrate into the brick along its pores, cracks and other capillary channels, and interact with it to form a metamorphic layer with different structure and properties of the original brick. When the temperature in the furnace fluctuates dramatically, the metamorphic layer will crack and flake, which is called structural spalling.

The corrosion of magnesia-chrome brick lining of copper smelting furnace is mainly caused by the reaction of solvent, slag and magnesia-chrome brick:

(1) In the smelting and blowing process, the iron in the matte is oxidized and added to the silica in the converter to produce ferriolivine slag, and the ferriolite reacts with the ferriolite in the magnesia-chrome brick to make the ferriolite dissolve in the slag;

(2) Adding silica in the converter can also react with cubic magnesite to produce magnesium olivine, so that the furnace lining is fused;

(3) The oxide of iron can saturate the ferromagnesite and chromite grains (ferrochromite spinel) and form a solid solution to form ferrochromite.

In summary, magnesia-chromium spinel shows good slag resistance, and the erosion of magnesia-chromium refractories by slag is mainly manifested as the melting corrosion of magnesia-chromium refractories.

3. Chemical erosion

Under the action of high temperature, the addition of soda ash or strong alkali in antimony refining process will aggravate the erosion of refractory materials. Alkaline oxides will infiltrate into the aluminum and silicon refractory to form low melting point of albite (Na2O·Al2O3·6SiO2 melting point of about 1100℃), will cause the refractory to melt or accompanied by volume expansion of "alkali crack" and damage, which is also the high aluminum brick in antimony smelting reverberatory furnace than magnesia chrome brick and chrome slag brick short life and be phased out of the reason.

4. Erosion and wear

The throat of the antimony smelting blast furnace is continuously eroded by the melt, and the damage is faster. The continuously pumped compressed air in the reverberatory furnace will drive the melt to churn, and the scour of the refractory material in the slag line area is particularly strong, resulting in the damage of the refractory material in this part. Serious, continuous erosion after the formation of a "U" shaped area, if the furnace is all the same material refractories, slag line parts of the refractory will be damaged in advance than other parts.