JPS609094B2 - Raw materials for ferroalloys - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses raw materials for ferroalloys, particularly chromium-containing birch produced when producing sodium chromate from chromium ore, to which chemical treatment is applied. Concerning effective use as raw materials.

In general, industrial production of sodium chromate involves blending chromium ore with an alkaline agent such as soda ash and caustic soda, and further adding lime and inert fillers as necessary.The mixture is then oxidized at high temperature. A method is adopted in which a sodium chromate aqueous solution is obtained by soaking the porcelain pottery in water. On the other hand, at this time, a large amount of chromium-containing leaching residue, chromium-containing ore, is formed, and its composition varies depending on the sintering conditions, type of ore, presence or absence of lime addition, etc., but in most cases it falls within the following range. It will be done. Weight% Among these, the Cr203 component mainly exists as trivalent chromium, but hexavalent chromium also exists in the form of 3,000 to 15,000
Contains about the legs.

Furthermore, since most of the Na20 component exists as a compound that is poorly soluble or insoluble in water, it is not eluted by normal leaching operations. Conventionally, such chromium ore has little practical utility value after recovering as much chromate as possible by increasing the leaching efficiency and has not been produced. Therefore, although it is normal to reduce the hexavalent chromium in the key chain to trivalent chromium using a reducing agent such as ferrous sulfate and dispose of it in a landfill, active and effective use of chromium-containing ore birch is being considered. This is not to say that it has not been done, but the following typical proposals have been made. First of all, after adding and mixing chromium-containing birch with a silicic acid substance and a reducing agent and granulating it, the granulated product is fired at a high temperature to form a granular porous silicate, which is used as a lightweight skeleton. ±Used for wood. (Special Publication No. 52-10094) Second, by applying acid to chromium-containing ore, some of the components such as Fe203, Aso203 and Mzao are dissolved, Aqueous solutions of these salts are used as sewage water treatment agents.(Japanese Patent Application Laid-open No. 11010/1983) However, among these usage methods, ``the former method of using them as lightweight aggregates involves adding a large amount of silicic acid to the melting point. It has the disadvantage of requiring large-scale equipment and a large amount of energy to heat at near high temperatures. It can hardly be called an industrial method.

In addition, the latter method of applying it to a water treatment agent is not a rational method since only one component of the chromium-containing mineral is used.

In any case, the active and effective use of chromite algae has not been made. Various studies have been carried out on the effective and efficient use of chromium-containing iron.The results of repeated studies have shown that a product with a specific composition obtained by chemically treating the keystone is extremely suitable as a raw material for the production of chromium-containing iron alloys. In view of this, we have completed the present invention.That is, the present invention is a reduction-neutralized product of chromium-containing ore produced when producing sodium chromate from chromium ore, which has at least A raw material for a ferroalloy characterized by having a chromium content of 1Q% by weight or more, a valuable component of iron and chromium of 2% by weight or more, and a soda content of 5% by weight or less.

According to the study results of the present inventors, chromium-containing minerals generally contain hexavalent chromium and Na20 components, which can cause environmental pollution. Therefore, it cannot be used as a raw material for ferroalloys.

Furthermore, even if used in a large amount, a large amount of Ca0 component will reduce the content of valuable components such as chromium and iron, resulting in the production of more slag than necessary in the process of producing ferroalloy, resulting in an increase in energy. However, ``Even if such Hina birch has been reduced and neutralized with mineral acids,
It has been found that chromite birch can be effectively used as a raw material for ferroalloy. Therefore, in the present invention, the reduced and neutralized product of chromium-containing birch means that the basic components of chromium-containing birch are neutralized with acid and at the same time, the hexavalent chromium contained is reduced to substantially eliminate hexavalent chromium. It means a treated product that does not contain.

In the present invention, among the above-mentioned reduction-neutralized products, those particularly applicable as raw materials for ferroalloys have a chromium content of about 1% by weight or more, preferably 12% by weight or more in terms of oxides. is about 2% by weight or more, preferably 3% by weight
It is necessary to have a content of each component of at least about 5% by weight, preferably at most 3% by weight of soda. The reason for this is that "the raw material for ferroalloy according to the present invention can be used by itself or in combination with other raw materials for iron manufacturing to effectively recover the valuable content; if it deviates from this range, the slag component may be too large" This is because large quantities of chromium-containing ore cannot be used as it may damage the furnace materials.Although it is possible to use various chromium-containing ore plates regardless of their history, due to their nature. It is preferable to have as much chromium as possible and a small amount of alkali and calcium.

On the other hand, acid is an essential raw material for modifying chromium-containing minerals to make them suitable as raw materials for ferroalloys, but depending on the processing method described below, the hexavalent chromium in the minerals can be converted to trivalent chromium. A reducing agent is used in combination for reduction.

Examples of such reducing agents include ferrous sulfate, sodium sulfide, sulfite, sulfites, thiosulfates, sulfur, activated carbon, glyoxal, and hydrazine. In addition, the acid elutes Nada-soluble Na20 components that cannot be eluted by simple water washing, and also removes excess Ca○, Mg○, and A〆203.
By dissolving slag components such as Cr20, which is a valuable component,
3 and Fe203 content, such as sulfuric acid, hydrochloric acid, mineral acids such as nitric acid, and organic acids such as formic acid and acetic acid. The industrial waste fluids discharged from various chemical factories or metallurgical processes, such as waste acids, are inexpensive and practical from the viewpoint of resource saving. can be manufactured.

Namely, there are two methods: a wet method in which a chromium-containing mineral, an acid, and a reducing agent are reacted in a slurry form for modification, and a dry method in which a mixture of the mineral mineral and acid is directly calcined, and then the soluble components are leached out. Two ways are representative. First, in the wet method, acid and
After adding a reducing agent in an amount equal to or more than the redox equivalent to valent chromium and carrying out a reaction until the final pH of the slurry becomes 4 or less, an alkali is further added as necessary to perform a neutralization treatment. The reaction is accelerated by heating. After the reaction is completed, solid-liquid separation is performed, and the filtrate cake is then washed and dried to produce a raw material for ferroalloy. During this drying, a suitable binder can be added to form granules. Next, in the dry method, acid is added to the chromium-containing ore in the presence of an appropriate amount of water, and the mixture is mixed uniformly by mulling or kneading.
Heat to 00-1000°C.

As a result, hexavalent chromium is substantially reduced, and after heating,
It is washed with water to separate and remove soluble components such as Na20, and further dried in the same manner as described above to be finished as a raw material for ferroalloy. Therefore, in this method, since hexavalent chromium is reduced by heating, a reducing agent is not necessarily a necessary chemical, but it can be used as appropriate depending on the properties of the ores to be treated and firing conditions.

The amount of acid in this method is the same as in the wet method, and is such that the pH of the slurry is about 4 or less.

In addition, in the reduction-neutralization treatment, chromium oxides, created substances generated from various factories containing hydrous oxides, and acidic substances containing chromium can be effectively used together as required. In addition, in any case, during drying, by-products can be effectively removed by mixing carbon materials such as coke, dust and scales generated during iron manufacturing, steelmaking, or metal processing with the above-mentioned processed materials and pelletizing them. This is more preferable because it can be recovered.

In this way, regardless of the method used, in the reductively neutralized product, alkali and other soluble components are substantially separated and removed, and valuable components such as chromium and iron are more concentrated than in chromium-containing mineral algae, while other components are Mainly A evening 2
03, Mg0 and Ca○ are slag-forming components in steelmaking, but these are particularly easily meltable and have a tendency to form highly fluid slag, making refining work easier, and are used as raw materials for ferroalloys. It can be effectively used as In this way, according to the present invention, chromium content including hexavalent chromium, which has been the most problematic in the chromium-containing mineral regulations, is reduced to Fe2.
It is completely recovered as a valuable resource with 0.3 minutes, and other components are also used as slag forming agents, so it does not just detoxify chromium-containing minerals, but also makes full use of its characteristics, making it possible to recover effective resources. can be achieved effectively.

Therefore, it can be said that it is the most appropriate purpose and has great industrial significance in these days when resource saving is being called for.

Next, examples of the present invention will be shown. Example Chromium-containing ore powder (particle size 175 mm) shown in Table 1 10
After reacting 0 parts by weight with 7.3 parts by weight of sulfuric acid, 9.0 parts by weight of ferrous sulfate, and 20 parts by weight of water in a tank, the solid and liquid are separated.

The obtained solid is washed with about 5 times the amount of water and then dried in a rotary kiln. The rotary kiln operates at a maximum temperature of 250°C and an average total time of 1. It was a time-consuming condition. This is referred to as raw material A for ferroalloy. The separated liquid was treated under normal wastewater treatment conditions. Table 1 (values are based on weight) Next, Table 2 shows the chromium-containing mineral powder (particle size 175)
10 parts by weight of sulfuric acid and 12.5 parts by weight of sulfuric acid were uniformly mixed and fired in a rotary kiln at a maximum temperature of 800°C and an average residence time of 2 hours.

After washing the baked product with 1 volume of water, the solid material was dried in a rotary kiln at a maximum temperature of 250 q and an average residence time of 1.5 hours. This is designated as raw material B for ferroalloy. Table 2 (values are based on weight) 18 parts by weight of silica stone, 1 part by weight of quicklime, and 10 parts by weight of coke are mixed with 10 parts by weight each of the raw materials A and B for ferroalloy obtained above. *After that, this mixture was placed in a Soederberg electric furnace. Approximately 1650 after entering
Melt processing was performed at oo.

The obtained treated products and recovery rates are as shown in Table 3. As is clear from the results in Table 3 and above, most of the chromium in the chromium-containing ores was recovered as ferrochrome, which was found to be effective as a raw material for ferroalloys.

Claims (1)

[Scope of Claims] 1. A reduced and neutralized product of chromium-containing slag produced as a by-product when producing sodium chromate from chromium ore, containing at least 10% by weight of chromium in terms of oxides, iron and chromium. A raw material for a ferroalloy, characterized in that the content of valuable components is 20% by weight or more and the content of soda is 5% by weight or less. 2. The raw material for a ferroalloy according to claim 1, wherein the reduced and neutralized product is wet-treated. 3. The raw material for a ferroalloy according to claim 1, wherein the reduced and neutralized product is dry-treated.
4. The raw material for a ferroalloy according to claim 1, wherein the reduced and neutralized product is in the form of pellets.