Stiff vacuum extrusion

— Innovative agglomeration


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Ferro Alloys production

Stiff vacuum extrusion technology, created by J. C. Steele & Sons, Inc., allows to effectively agglomerate various anthropogenic and natural materials and fuels (like coke and coals), attributing high metallurgical properties to the agglomerated products and to consider them as attractive charge components for the majority of different metallurgical processes and furnaces. The first successfully realized project of the company in this direction is the utilization of BREX in the charge for smelting of Ferro-nickel at the enterprise belonging to BHP Billiton in Cerro Matoso (Montelibano, Colombia; identified resources for 2006-99 million tons with nickel content 1.54%) There are three stiff extrusion lines based on the Steele-90 Extruders. These extruders agglomerate fines of lateritic nickel ore for the further metallization of the BREX in the rotating kilns and finally for their use as the charge components of the Electric Furnace for Ferro-nickel smelting.

The dust is being generated during the crushing of the ore lumps as well as in the aspiration systems of the kilns and furnaces. Total capacity of the plant – 700 kty of BREX.   

A specific feature of lateritic nickel ore agglomeration by stiff extrusion is the lack of need in binder. The average capacity of one extruder-70 t/h. Based on the results of the industrial operation of extrusion lines in 2004-2010 the self-cost of manufacture of 1 t of BREX has not exceeded $ 2.1. The life cycle of the extrusion equipment-more than 30 years. Nickel production calculated through its content in Ferro-nickel is 50000 tons per year, of which 10000 tones comes through BREX.

Successful results shown under industrial use of stiff extrusion in Columbia, drew attention to it from the other largest mining company in the world-VALE. At its plant in Onca-Puma (Brazil, identified resources 423.3 million tons, nickel, content 1%) There are also three extrusion lines for agglomeration of small fractions of laterite nickel ores. Annual production of BREX is also 700 kty.

Systematic research of the applicability of the stiff extrusion for agglomeration in Ferroalloy industry was first taken V. Ya.Dashevskyi, A.V.Pavlov and A.M. Bizhanov in 2010. Metallurgical properties of the BREX on the basis of natural and anthropogenic raw materials were investigated for Ferrochrome smelting as well as for the Manganese Ferroalloys. On request of one of the world's largest producers of Ferrochrome in the laboratory of the J. C. Steele & Sons, Inc. in the United States the sample BREX of a set of different compositions comprising ore fines, aspiration dusts and coal fines were manufactured and further tested in Moscow Institute of Steel and Alloys in Moscow. The materials after mixing and addition of the required amount of water showed high plasticity, good extrusion with the formation of a strong "green" BREX. After daily curing under natural conditions their compressive and tensile splitting strength values were measured. It turned out that even for laboratory BREX adding of less than 5% of Portland cement produces strength values required by specifications.

On request of one of the largest producers of manganese ferroalloys in the 2010-2011 A.M. Bizhanov with colleagues has performed a complex research ended with the full-scale industrial testing of silicomanganese smelt based on the charge with high ratio of BREX in the ore part. The results of the campaign have shown high efficiency of BREX use for the production of manganese alloys. Pilot campaign itself passed without visible changes of the technological process: furnace (SEAF) worked smoothly, with constant current load, release melt occurred on schedule, without significant changes in the chemical composition of the metal and slag, gas permeability of the furnace top has improved. Specific consumption of electricity in an experienced period has decreased significantly. Electricity consumption in the base period for 1 ton of alloy was 4091 kWh.

When feeding 40% of BREX into the charge specific electricity consumption fell to 3727 kWh per 1 ton of alloy. Another positive campaign results is the increase in the level of the manganese extracted. During the basic period of operation without BREX the extraction of manganese was at averaged 80%, with BREX (30% in the charge) extraction of manganese reached 83.5%.

Such results of full-scale experiment confirm applicability of the BREX as the essential part of the charge for production of Ferro Alloys.