RU2339464C1 - Method of processing magnesium-containing solid waste - Google Patents

Abstract

FIELD: chemistry; process flows.

SUBSTANCE: method includes grinding of solid magnesium-containing wastes with maximum moisture content 1% by weight and minimum magnesium content 14% by weight in equivalent of elementary magnesium in ball mills with maximum particle size 200 mcm with production of magnesia cement.

EFFECT: improved environmental situation nearby industrial facilities with simultaneous production of magnesia cement.

2 cl, 3 ex

Description

The invention relates to the field of metallurgy and chemical technology for the processing of inorganic substances and can be used in enterprises processing magnesium-containing ores, in particular the processing of magnesium-containing waste products, preferably in the form of solid magnesium-containing sludge.

The invention can be used, in particular, for processing various solid wastes of the production of magnesium-containing minerals such as magnesite, dolomite, carnallite, bischofite, cainite, olivine, kizerite, brucite, as well as poor ores containing these minerals. When implementing the method, it is desirable to use a feedstock (solid waste or lean ores) containing not less than 14% magnesium (in terms of magnesium element), and it is preferable to use raw materials containing magnesium in the form of oxide and / or water-soluble salts. In particular, waste sludge is subject to processing, in particular carnallite sludge, serpentinite dumps, magnesite processing waste, waste slag, cake, etc.

Known (RU, application 2003105081/15) is a method for processing magnesium-containing waste. According to the known method, grinding of feedstock, opening of waste, separation of phases, separation of target products is carried out, carnallite chlorine sludge is used as feedstock, and opening is carried out by interaction of sludge with water, the wash water formed is separated from the insoluble precipitate, insoluble precipitate is recovered subjected to drying to obtain magnesium oxide, and the washing water is subjected to evaporation to obtain synthetic carnallite.

The disadvantage of this method is its unsuitability for the processing of carnallite chlorinator sludge containing compounds of magnesium chloride and magnesium oxide of high concentration, which when combined with water form solid compounds such as Sorel cement, which leads to clogging of the equipment and a decrease in the productivity of the process.

Also known (RU, patent 2291107) is a method for processing salt waste from magnesium production, including grinding the feedstock, opening the waste by interacting with water, phase separation, isolation of the target products, drying the precipitate to obtain magnesium oxide and evaporation to obtain a concentrated solution of metal chlorides, before opening, the waste is treated with flue gases with a water content of 11.3-18.5 vol.% in a fluidized bed furnace at a layer temperature of 300-600 ° C. The treatment of magnesium waste salt waste with a mixture of flue gases by heat treatment at a temperature of 300-600 ° C allows shifting the hydrolysis of magnesium chloride to the direction of producing magnesium oxide, which can significantly increase the degree of extraction of magnesium oxide from the waste, reduce the degree of deposition of solid phase on the equipment, and thereby increase installation performance.

The disadvantage of this method should recognize its technological complexity.

The technical problem solved by the developed technical solution is to create a simple technology for processing solid waste containing magnesium.

The technical result obtained by the implementation of the developed technical solution consists in improving the environmental situation near industrial enterprises processing magnesium-containing raw materials, while obtaining a magnesian binder.

To achieve the technical result, it was proposed to use grinding of solid magnesium-containing raw materials, which is waste from the processing of magnesium-containing minerals or poor magnesium ores, containing not more than 1 wt.% Moisture and not less than 14 wt.% Magnesium in terms of elemental magnesium, in ball mills to obtain particles with a size of not more than 200 microns, while grinding is carried out for no more than 1 day after removing the sludge from the chlorinator. The crushed material is preferably placed in a container that isolates it from the environment (plastic bags, Kraft bags), and placed in storage. However, the crushed material (magnesia binder such as Sorel cement) can be immediately used for the production of building materials or construction work. If necessary, excess moisture is removed from the starting magnesium-containing raw material.

When the moisture content exceeds 1 wt.%, A water-soluble salt of magnesium and magnesium oxide are combined to form compounds such as Sorel cement. When the magnesium content is less than 14 wt.%, The resulting magnesian binder does not provide reliable quality of building materials, and also does not provide the strength of building elements, which include the resulting binder. When grinding magnesium-containing waste with obtaining particles larger than 200 microns in size, the resulting magnesian binder does not provide reliable quality of building elements, and also does not provide the strength of building elements, which include the resulting binder. The use of metallurgical or chemical production wastes (in particular sludge) that have lain in dumps for more than 1 day is impossible, since it is no longer possible to activate magnesium compounds by mechanical grinding due to the fact that at an ambient humidity of 60-70% and more dehydrated during production with the receipt of these wastes, water-soluble salts of magnesium contained in the sludge, in the presence of moisture, begin to actively react with magnesium oxide. In this case, the surface of the blade becomes loose to a depth of 10-15 cm. Thus, the amount of water-soluble salts of magnesium and magnesium oxide decreases sharply and the use of sludge as a binder becomes problematic.

When the dispersion of crushed waste within 50-200 microns, the composite mixture works in the range of ratios of the main components involved in the formation of magnesia cements, with the production of magnesia cement, the setting of which begins not earlier than 25 minutes, and the end of setting no later than 5.5 hours with a mass fraction of moisture not more than 1 wt.%.

In the future, the essence of the developed technical solution will be disclosed using implementation examples.

Example 1. To obtain a magnesian binder used in the technology of warm plaster, carnallite sludge containing 1 wt.% Moisture and 14.5 wt.% Magnesium in terms of elemental magnesium was crushed in ball mills with metal balls to obtain a particle size of not more than 170 microns, while grinding was carried out for 12 hours after extraction of the sludge from the chlorinator. Then, 15 kg of caustic magnesite was added to 100 kg of ground sludge, mixed for 5 min, sawdust of hardwood in the amount of 0.4 kg of sawdust per 1 kg of mixture was added, poured into water in the amount of 0.5 kg of water per 1 kg of mixture, mixed for 2-3 minutes, kept the mixture for 2 minutes and re-mixed.

The resulting stucco mixture should be used within no more than 100 minutes.

Example 2. To obtain a magnesian binder used in the technology of slurry waterproofing, serpentinite dumps containing 0.8 wt.% Moisture and 16.7 wt.% Magnesium in terms of elemental magnesium were crushed in ball mills with metal balls to obtain a particle size not more than 150 microns. Then, to the 100 kg of ground serpentinite dump, 40 kg of carnolite sludge was added, mixed for 6 minutes, sawdust of coniferous trees with an average particle size of up to 3 mm in the amount of 25 kg was added, mixed for 3 minutes, filled with water in the amount of 0.4- 0.5 kg of water per 1 kg of the mixture was mixed for 3-5 minutes until a creamy mass was formed, which was used as a waterproofing.

Example 3. To obtain a magnesian binder used in the technology of warm slurry floor, carnallite slurry containing 0.7 wt.% Moisture and 19.5 wt.% Magnesium in terms of elemental magnesium was crushed in ball mills with metal balls to obtain size particles not exceeding 200 microns, while grinding was carried out within 10 hours after extraction of the sludge from the chlorinator. Then, 14 kg of caustic magnesite was added to 100 kg of ground sludge, mixed for 5 minutes, sawdust of coniferous trees with an average particle size of up to 3 mm in an amount of 30 kg was added and lumpy wood waste with an average size of up to 35 mm in an amount of 17 kg, was mixed for 3 minutes and shut with water in the amount of 0.5 kg of water per 1 kg of the mixture, mixed for 3-5 minutes.

The resulting composition was laid out on a prepared floor base.

Using the developed method allows to improve the environmental situation near industrial enterprises that process magnesium-containing raw materials, while obtaining a magnesian binder.

Claims (2)

1. The method of disposal of magnesium-containing solid waste, including grinding solid magnesium-containing waste, characterized in that the processing is subjected to waste containing not more than 1 wt.% Moisture and not less than 14 wt.% Magnesium in terms of elemental magnesium, in ball mills to obtain size particles not exceeding 200 microns to obtain a magnesian binder. 2. The method according to claim 1, characterized in that during the processing of carnallite sludge, grinding is carried out for no more than 1 day after removing the sludge from the chlorinator.