RU2432332C1 - Method of producing alumina cement and manganese-aluminium alloy (versions) - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to production of alumina cement. In one version of the method of producing alumina cement and an alloy, involving preparation of mixture components, mixing said components, loading into an electric furnace, melting and outlet of the melt from the furnace, pouring into moulds, cooling and grinding, the mixture components used are ore with manganese content of 40-60 wt %, limestone with manganese content of 6-15 wt % and lime, outlet is carried out into a bucket on a reducing agent - aluminium; after holding for 7-10 minutes, said pouring is carried out from the bottom of the bucket by first draining the molten manganese-aluminium alloy and then the rest of the melt, with the given ratio of components. In another version of the method of producing alumina cement and an alloy, involving preparation of mixture components, mixing said components, loading into an electric furnace, melting and outlet of the melt through two separate streams into buckets, cooling and grinding to obtain two products - alumina cement and an alloy, the mixture components used are ore with manganese content of 40-60 wt %, limestone with manganese content of 6-15 wt %, lime, and a reducing agent - aluminium; loading is carried out in two steps - first said ore, limestone, lime and aluminium metal in amount of 30-40% of total content thereof, and after melting - the rest of the amount of aluminium; outlet of the melt is carried out after 15-30 minutes, with given ratio of components. ^ EFFECT: possibility of using limestone with high content of impurities, obtaining alumina cement with low heat release and stable strength in 28 days of age, non-waste technology which enables to obtain a manganese-containing alloy into which up to 90-95% manganese is transferred. ^ 2 cl, 3 ex

Description

The invention relates to the production of alumina cement.

A known method of producing high alumina cement by preparing components - lime and alumina, mixing them, melting the resulting mixture with the addition of alumina in an electric arc furnace, releasing the melt into bowls, cooling and grinding (a.s. No. 1300856, published 04.07.1984).

A known method involving the integrated processing of ore and comprising preparing the components and mixing them with melting the charge in a multifunctional melting unit - MPA when using aluminum as a reducing agent, removing the products obtained from the MPA - secondary slag, which is a high-alumina cement clinker and titanium-containing ligature ( RF patent No. 2228967, publ. 05/20/2004).

The closest analogue is a method for producing alumina cement and an alloy of ferrosilicon - ligature, which includes preparing components - bauxite and pure limestone, mixing them, melting the resulting mixture in an electric furnace using coke as a reducing agent, releasing the melt into two separate flows into molds, cooling and grinding with the receipt of two products - alumina cement and ferrosilicon ligatures (Volzhensky A.V., Burov Yu.S., Kolokolnikov BC Mineral binders. M., 1973, S. 466-449). Moreover, it is known that high-quality ferroalloys can be obtained, for example, ferromanganese by a furnace process, including the preparation of charge materials - manganese ore and lime with fluorite, feeding the charge into an electric furnace, smelting the melt, mixing it in a special reactor with ferrosilicon, aluminum, and other reducing agents in an amount of 10% less stoichiometrically necessary. Additionally, lime is introduced into the reactor. The residual content of manganese (II) oxide in the slag is in the range of 15-20%, which corresponds to the extraction of manganese in the metal in the range of 68-70%. Other disadvantages are the impossibility of using poor manganese raw materials in the processing, in particular, to re-establish toxins of own production; high losses of manganese with slag (depending on its content in the feedstock can be from 25 to 33%); the slag obtained in this case is unsuitable for further use as a marketable product and sent to the dump.

A disadvantage of the known methods is the high demands on the quality of the used components of the charge - a strict restriction on the limiting contents of the main oxides of the raw materials used.

The objective of the claimed invention is the provision of the possibility of using limestone with a high content of impurities, the production of alumina cement with reduced heat and stable strength at 28 days of age, the creation of waste-free technology that provides ligatures of manganese-containing, which goes up to 90-95% manganese.

This goal is achieved by the fact that in the method of producing alumina cement and ligature, including preparing the components of the mixture, mixing them, loading into an electric furnace, melting and releasing the melt from the furnace, casting the molds, cooling and grinding, ore containing manganese is used as the components of the mixture 40-60 wt.%, Limestone with a manganese content of 6-15 wt.% And lime, the release is carried out in a bucket on a reducing agent - aluminum, after holding for 4-10 minutes, the specified spill is carried out from the bottom of the bucket by first draining the melt and manganese-aluminum alloys, then the rest of the melt, in the following ratio of components, parts by weight:

specified ore one hundred specified limestone one hundred lime 0-10

aluminum - in an amount 1.1-1.8 larger stoichiometrically necessary for the complete reduction of manganese oxides in the charge.

According to another variant, in the method of producing alumina cement and ligature, which includes preparing the components of the mixture, mixing them, loading into an electric furnace, melting and releasing the melt with two separate streams into molds, cooling and grinding to obtain two products, alumina cement and ligature, respectively, as components the charges use ore with a manganese content of 40-60 wt.%, limestone with a manganese content of 6-15 wt.%, lime and a reducing agent - metal aluminum, loading is carried out in two stages - first indicated e ore, limestone, lime and aluminum in an amount of 30-40 wt.% from its total content, after their melting - the remaining amount of aluminum, the release of the melt is carried out after 15-30 minutes, in the following ratio, wt.h .:

specified ore one hundred specified limestone one hundred lime 0-10

aluminum metal - in an amount 1.1-1.8 larger stoichiometrically necessary for the complete reduction of manganese oxides in the charge.

The method of smelting a manganese-containing alloy is based on the reaction

3MnO + 2Al + CaO = 3Mn + Al ₂ O ₃ · CaO.

In the slag formed as a result of the above reaction, there are mainly only aluminum and calcium oxides, which, with a selected ratio of components, provide a fairly low melting point - below 1600 ° C. The sum of other oxides should be no more than 10-12%. Their presence is necessary to lower the melting temperature of the mixture, to ensure high activity of manganese oxide and improve conditions for a more complete transition of manganese into the alloy.

In the final slag-clinker of alumina cement containing a small amount of manganese oxides, its main components are aluminum and calcium oxides. A large temperature interval between the solidus and liquidus lines contributes to a more complete separation of the metal and slag phases, and therefore smelting can be carried out without noticeable metal losses in the form of kings entangled in the slag.

Investigations of the physicochemical properties of the Al ₂ O ₃ -CaO system showed that the amount of CaO taken in a certain ratio to Al ₂ O ₃ reduces the viscosity of the melts and increases the interfacial tension at the reduced metal – clinker alumina cement interface.

The following materials were used.

Manganese ore with a manganese content of 40-60 wt.%, Manganese concentrate, as well as technical manganese oxide, which can have, for example, the composition shown in table 1, can be used in the same quality.

Table 1 presents a typical chemical composition.

Table 1 Material Content% Mn MnO CaO SiO ₂ Al ₂ O ₃ P ₂ O ₅ FeO Manganese concentrate 1 grade 43.5 56.2 3.8 16.5 2.5 0.44 2,8 Technical Manganese Oxide II 60.0 77.4 2.0 12.0 5,0 0.04 1,0

Limestone with a manganese content of 6-15 wt.%.

Quicklime with a CaO content of 65-90 wt.%.

A study of the viscosity of manganese-containing slag shows that it depends on the amount of flux in the mixture. It has been established that the viscosity of slag during the smelting of manganese-containing alloys without flux is equal to about 0.8 N · s / m ² at a temperature of 1900 ° С, the addition of lime to the charge in an amount of up to 10 parts by weight, i.e. up to 40% by weight of the reducing agent, reduces the viscosity to 0.2 N · s / m ² .

Below are the results of a study of the CaO-Al ₂ O ₃ - slag system (alumina cement) as applied to the selected conditions for the smelting of manganese-aluminum alloys with a constant aluminum content in the charge equal to 1.5 from stoichiometry for the complete reduction of manganese oxides.

Melting without giving lime to the mixture. The metal-slag interface is uneven; the slag is poorly separated from the metal. Manganese distribution: in a metal ingot - 35%, remained in the slag - 58%, in the kings - 7%.

Melting with the addition of 20% CaO. The metal-slag interface is even, the separation of metal from slag is good, the extraction of manganese into the alloy increased to 54.9%, and 41.3% of manganese remained in the slag.

Smelting with the addition of 40% CaO. The metal separation is the same as in the previous heat. The extraction of manganese in the ingot was 86.3%, 11.7% of manganese in the form of the smallest kings and unreduced manganese oxide remained in the slag. The presence in the charge, in addition to calcium and aluminum oxides, of impurities in concentrations of less than 5% has a negligible effect on viscosity indices.

From an analysis of the processes of interaction of aluminum with charge oxides at the initial stages of the reduction process, it was found that the melting temperature of most oxides present in manganese-containing raw materials is much higher than the melting temperature of aluminum; therefore, capillary and interfacial phenomena can play a decisive role, thereby increasing the contact of aluminum with slag melt and improved conditions for the dissolution of the reduced elements in aluminum and their transition into a ferroalloy.

The following are examples of the execution of the invention, not excluding others in the scope of the formula.

In one embodiment, the following was carried out.

All constituent components of the mixture were first crushed to a fraction of 5 mm, then grinded to a particle size of 1 mm; after which each component was weighed in accordance with the composition of the mixture; mixed in a mixer until a homogeneous mass. The melts were carried out by an electric furnace at a temperature of 1500 ° C, then the melt was poured into a ladle, from where after 5 minutes, the ligature melt was first poured into the molds from the lower part, and then the remaining melt was poured into the molds, after cooling it was milled, in this example 3500 cm ² / g and determined the properties of the obtained alumina cement. Studies have shown: the content of manganese aluminate in it is up to 5 wt.%, Heat release is 50 J / g, the strength increase for grade 500 on the first day 30-34 MPa, after 3 days 60 MPa, after 28 days there is no decrease in strength. Typical alumina cement is heat release of 70 J / g and late fall in strength compared to strength at 3 days of age.

Example 1

The ratio between the components of the charge is as follows, parts by weight: manganese ore with a Mn content of 50 wt.%, 100, manganese limestone with a Mn content of 12 wt.%, 100, aluminum with an Al content of 88 wt.%. 27, i.e. 1.5 times more stoichiometrically necessary. Methodology for conducting experiments on the smelting of manganese-containing alloys

Example 2

The ratio between the components of the charge is the following, parts by weight, lime 5, manganese ore with a Mn content of 60 wt.%, 100, manganese limestone with a Mn content of 15 wt.%, 100, aluminum with an Al content of more than 88 wt.%, 39, those. 1.8 times more stoichiometrically necessary, lime 10.

In another embodiment, the following was carried out.

All constituent components of the mixture were first crushed to a fraction of 5 mm, then grinded to a particle size of 1 mm; after which each component was weighed in accordance with the composition of the mixture; mixed in a mixer until a homogeneous mass is obtained, loading was carried out in two stages - first, through filling the mixture of ore, limestone, lime and parts of the total amount of aluminum, after they were melted by an electric furnace at a temperature of 1500 ° C, the remaining amount of aluminum was loaded through a window in the furnace, then, after 15-30 minutes, the ligature melt was discharged, and then the slag was poured into the molds, after cooling it was milled, in this example 3500 cm ² / g, and the properties of the obtained alumina cement were determined. Studies have shown: the content of manganese aluminate in it is up to 5 wt.%, Heat release is 45 J / g, the increase in strength on the grade 500 on the first day is 32-35 MPa, after 3 days 63 MPa, after 28 days there is no decrease in strength. Typical alumina cement is heat release of 70 J / g and late fall in strength compared to strength at 3 days of age.

Example 3

The ratio between the components of the charge is the following, parts by weight: manganese ore with a Mn content of 50 wt.%, 100, manganese limestone with a Mn content of 12 wt.%, 100, aluminum with an Al content of 88 wt.%, 27 - i.e. . 1.5 times more stoichiometrically necessary. Moreover, at the first stage, 35% of aluminum was introduced, and at the second, the remaining 65% of its total content.

An analysis of the experiments shows that the use of manganese ore and manganese limestone in the mixture, taken at a certain ratio, improves the technological parameters of the smelting process by reducing the melting temperature of the mixture, i.e. at the same melting temperatures, the slag mobility increases and thereby more complete precipitation of the kings of reduced manganese in the slag volume and their better separation are achieved.

The technology can be implemented at any of the existing ferroalloy plants, for example, at the Klyuchevsk ferroalloy plant or organized without major capital investments in a new place.

The resulting products — alumina cement and ligature, respectively, have the following properties: cement — a stable increase in strength and reduced heat generation, and ligature — an increased content of manganese in the alloy.

Claims (2)

1. A method of producing alumina cement and ligature, including preparing the components of the charge, mixing them, loading into an electric furnace, melting and releasing the melt from the furnace, casting into the molds, cooling and grinding, characterized in that ore containing manganese content 40 is used as the components of the mixture -60 wt.%, Limestone with a manganese content of 6-15 wt.% And lime, the release is carried out in a ladle on a reducing agent - aluminum, after exposure for 4-10 minutes, the ligature and slag melts are separated, first melt from the bottom of the bucket and manganese-aluminum alloys, then the rest of the melt, in the following ratio of components, parts by weight:
specified ore one hundred specified limestone one hundred lime 0-10
aluminum - in an amount 1.1-1.8 larger stoichiometrically necessary for the complete reduction of manganese oxides in the charge. 2. A method of obtaining alumina cement and ligature, including preparing the components of the mixture, mixing, loading into an electric furnace, melting and releasing the melt with two separate streams into the molds, cooling and grinding to produce two products, alumina cement and ligature, respectively, characterized in that As components of the charge, ore with a manganese content of 40-60 wt.%, limestone with a manganese content of 6-15 wt.%, lime and a reducing agent are aluminum, aluminum is loaded in two stages — first, they charge the ore, limestone, lime and aluminum in the amount of 30% -40% of its total content, after the charge is melted - the remaining amount of aluminum, the melt is released after 15-30 minutes, with the following ratio of components, parts by weight:
specified ore one hundred specified limestone one hundred lime 0-10
aluminum - in an amount 1.1-1.8 larger stoichiometrically necessary for the complete reduction of manganese oxides in the charge.