Within the framework of the project "Development and improvement of the technology for smelting refined ferromanganese grades from Kazakhstan's low-quality manganese raw materials" by the scientists of the Chemical-Metallurgical Institute named after Zh. Abishev developed a technology for smelting refined manganese ferroalloys with aluminum silicothermic method, using aluminum-silicon manganese as a reducing agent.

The purpose of the work is to master and improve the technology of smelting refined ferromanganese grades from Kazakhstan's low-quality manganese raw materials.

The steady growth of world steel production observed in the last decade is associated with the inherent growing demand of ferrous alloys for the metallurgical industry. The most used are manganese-containing ferroalloys (high- and low-carbon ferromanganese, silicon manganese, metallic manganese).

The bulk (about 95%) of manganese, most important strategic metal, is produced in the world in the form of ferroalloys (ferro- and ferrosilicon manganese, complex manganese-containing alloys) and is used in the smelting of various types of steels as a deoxidizer and alloying additive. Therefore, the increase in steel production is accompanied by an increase in the extraction of manganese ores and smelting of manganese ferroalloys. For example, only in 2010 the world production of manganese alloys increased by 25%, or up to 14.6 million tons by total weight. Note that the major share in the world production of manganese alloys is ferrosilicon manganese with a share in production of 59.5%. The volume of ferrosilicon manganese production in 2010 increased by 18%, or up to 8.7 million tones, and the production of high-carbon ferromanganese increased by 34% to 4.7 million tones, low- and medium-carbon ferromanganese increased by 48%, or to 1.5 million tons.

According to scientists, the forecast reserves of manganese-containing ores of the Republic of Kazakhstan together with the explored deposits are about 700 million tons. In recent years there has been a steady demand for manganese alloys, smelted from Kazakhstan's low-phosphoric concentrates, and an increase in the extraction of manganese ore began. So, for the period of 1991-2003, there was a sharp increase in the level of the repayment of reserves from 330 thousand tons to 2,369.0 thousand tons, i.е. the extraction of manganese ore by the mining industry of Kazakhstan increased by 8.5 times. Thus, in the period 2003-2008, the volume of extraction of manganese ores increased by 4.7%, ie from 2.369 to 2.485 million tons.

Manganese ore deposits are being developed: Ushkatyn III, Karaadyr, Tur, Esymzhal, Zhomart, Aitkokshe, Sarytun, Shointas, Chuldak, Western Karazhal, Bogach, East and West Kamys. There are Zhayremsky ore mining and processing enterprise and Zhezdinsky concentrating mill. The Kazakh manganese raw material is operated by the Chelyabinsk Electrometallurgical Combine.

The main producer of manganese alloys is the Aksu Ferroalloy Plant, where for the first time in the Republic of Kazakhstan the production of ferrosilicon manganese is organized. Currently, out of the 6 furnaces of workshop No. 1 of the RKZ 33 MVA, 4 furnaces have been completely transferred from production to ferro-silicon for silicon manganese, with the production of alloys exceeding 120-140 thousand tons per year and consuming more than 0.5 million tons of concentrate.

At the Temirtau Chemical-Metallurgical Plant LLP, after the reconstruction of the V-20 workshop, the production of ferrosilicon manganese in the volume of up to 25-45 thousand tons per year was organized using the technology developed by the Chemical and Metallurgical Institute (Karaganda), and the production of the second furnace.

In addition, manganese ore concentrates are supplied to Russia (at the Chelyabinsk Electrometallurgical Combine and the Serov Ferroalloy Plant).

To date, the production of refined ferromanganese grades has not been organized in Kazakhstan, although over the 20 years of independence it has been possible to create new production and increase the smelting volumes to 200 thousand tons of ferrous manganese per year. Thanks to scientific developments of ferro-alloy-scientists ChMI named after Zh. Abishev, the following idle production was reoriented for the smelting of ferrosilicon manganese:

- Ferrosilicon furnaces of the Aksu ferroalloy plant (with a capacity of up to 160 thousand tons per year for ferrosilicon manganese);

- carbide furnace of the Temirtau Electrometallurgical Combine (with a capacity of up to 25 thousand tons of ferrous silicon manganese per year);

- phosphoric furnaces of LLP "Khimprom -2030" (currently Taraz Metallurgical Plant LLP (with a capacity of up to 15 thousand tons per year).

In Kazakhstan, there are all prerequisites for expanding the range of manganese ferroalloys produced, which is achievable due to the organization of the production of refined ferromanganese brands, namely manganese raw materials base, scientific potential and idle electric arc furnaces of refining type. In addition, there is a need for refined ferromanganese brands of steel smelters steel Hadfield for mining equipment.

As a result of the research, pilot-industrial tests were carried out and the main technological parameters of the smelting of medium-carbon ferromanganese were worked out. An experimental batch of medium-carbon ferromanganese and a new complex reducing agent, aluminosilico manganese, have been developed. The main technical and economic parameters of smelting of medium-carbon ferromanganese are determined. It has been established that manganese ores of the West Kamys and Aitkoksha deposits can be used as a raw material for the smelting of the aluminosilico manganese and the refined ferromanganese without deep enrichment.

In large-scale laboratory conditions, it was established that a new type of complex reducing agent, aluminosilico manganese from high-ash coals of the Saryadyr and Borli deposits, high-silicic manganese ores of the Aitkokshe and Western Kamys deposits, can be obtained in a one-stage carbothermic slag-free process. The data obtained make it possible to develop an integrated and resource-saving technology for the smelting of a new type of silicon-aluminum reductant, which can be used in the steelmaking industry as a deoxidizer, and as a reducing agent in the production of medium- and low-carbon ferromanganese grades. As a result of large-scale tests, the following was established:

- the main electrical parameters of the smelting technology of aluminosilico manganese - operating voltage 24-36 V current 3200-3500 A;

- the degree of extraction of basic elements reaches 84.8-90.87% manganese, 76.5-83.53% silicon and 68.9-76.57% aluminum;

- the necessary degree of excess of solid carbon, which is 10-15%. For comparison: ferrosilicoaluminum is smelted with a shortage of solid carbon of 3-5%;

- possibility of complete replacement of metallurgical coke as a reducing agent, high-ash and low-ash coals of the Saryadyr, Borly and Shubarkol deposits;

- the principle possibility of obtaining a new type of complex alloy, in terms of chemical composition, characterized by a high content of aluminum, up to 22-26%.

The feasibility of smelting a medium-carbon ferromanganese of FeMn90C20 and FeMn90C20LP (ISO 5446-80) grades with the use of a complex reductant of aluminosilico manganese and FeMn80C20LP and FeMn80C20 grades using ferro-silicon manganese was experimentally tested.

Development of recommendations and initial data on the specific use of results. The data obtained make it possible to use smelting of medium-carbon ferromanganese as initial charge materials: poor high-silica manganese ores of Aitkokshe and West Kamys fields without preliminary enrichment (increasing through manganese extraction), low-ash and high-ash coals, which significantly reduces the cost of production.
The main electrical parameters of the technology are operating voltage 49 V and current 1160-1900 A. According to the results of work it can be concluded that the connection of transformers is necessary for constant and continuous operation of the refining furnace not in parallel, as it was during the tests, but consistently, which will allow increase the voltage to 98V. The need to increase the operating voltage is due to the fact that 90-95% of the carbon enters the final metal from the electrodes. Therefore, an increase in the productivity of the furnace due to an increase in the current and the power taken off led to an increase in the carbon content in the medium-carbon ferromanganese, i.e. reduced its grade.

The developers assessed the technical and economic efficiency of the implementation. Thus, the capacity of a semi-closed refining furnace is 350-500kg of medium-carbon ferromanganese per day, which allows, with some modernization of the furnace unit, to provide the annual demand for a ferromanganese of such a large enterprise as Kazakhmys Corporation. To fully meet the needs of the industry of the Republic of Kazakhstan in the medium-carbon ferromanganese, it is sufficient to install furnace capacities of 1 MVA, which will allow to smelt, according to the developed technology, about 1.5-2.5 thousand tons of refined ferromanganese per year.

In addition, the obtained results confirm the conclusion made about the economic and technological feasibility of organizing the production of medium-carbon ferromanganese according to the developed technology in the scale of mini-production to provide the domestic market with the subsequent prospect of entering the world market. Approximate production volumes in monetary terms to ensure only domestic demand can reach about $ 4.5-6 million dollars.

Due to the use of slag-free carbothermic technology and the use of re-slag slag (formed during smelting of medium carbon ferromanganese) at the stage of smelting of aluminum silicomanganese and ferro-silicon manganese, it is possible to increase the degree of manganese use by 10-15% (so much is usually lost with slag from the smelting of ferrosilicon manganese) reduce the cost of the final product.

The scientists emphasize that the feature of the technology being developed is the possibility of replacing ferrosilicon manganese (a traditional reductant in the smelting of refined ferromanganese) by a cheaper reducing agent – aluminosilicon manganese. The use of poor high-silica manganese ore and high-ash coal as a raw material in the smelting of aluminosilicon manganese instead of manganese ore and coke nut (in the production of ferrosilicon manganese) can significantly reduce the requirements for raw materials and the cost of the refined ferromanganese to be

refined. At the same time, as the developers say, there are no world analogues for obtaining refined ferromanganese by the aluminosilicothermic method.

Department of Public Relations of JSC “NCSSTE”