RU2148093C1 - Method of preparing iron concentrate - Google Patents

Abstract

FIELD: metallurgy, more particularly recovery of iron concentrate from ash- slag waste resulting from combustion of coals at thermal electric stations. SUBSTANCE: ash pulp is prepared by combustion of fuel whereupon pulp is first subjected to magnetic separation at magnetic field intensity of 50-90 KA/m, and the resulting magnetic fraction is divided to particle size of 0.2-0.63 mm and once again subjected to magnetic separation at magnetic field intensity of 20-70 KA/m. EFFECT: improved quality of the iron concentrate and reduced cost price thereof. 3 tbl

Description

 The invention relates to the field of metallurgy, and in particular to methods for producing iron concentrate from ash and slag waste of coal burning at thermal power plants.

 A known method of producing iron concentrate from ash, which consists in obtaining pulp, a three-stage classification of the material, followed by magnetic separation of the densest fraction (US patent N 5227047).

 The disadvantage of this method is the low iron content in the concentrate, because it is difficult to separate the iron from the accompanying compounds without grinding the starting material.

 As a prototype, a method was selected for extracting materials from ash obtained by burning fuel, which consists in magnetic separation of ash, two-stage screening of the magnetic fraction, grinding of the intermediate screening product with its subsequent magnetic separation (European patent N 0257434).

 The disadvantage of this method is the low quality of the iron concentrate due to the large number of thin classes of silicate materials in it that are not amenable to dry magnetic separation, as well as the high cost of the concentrate, because it is necessary to grind a large amount of material.

 The problem solved by the proposed invention is to improve the quality of iron concentrate and reduce its cost.

 This problem is solved in that in the known method for producing iron concentrate, including preliminary magnetic separation of ash from fuel combustion, grinding of the magnetic fraction and its repeated magnetic separation, the ash pulp from fuel combustion is first obtained, after which the pulp is subjected to preliminary magnetic separation at a magnetic field 50-90 kA / m, the resulting magnetic fraction is crushed to a particle class of 0.2-0.063 mm and subjected to repeated magnetic separation at a magnetic field strength of 20-70 kA / m.

 As a result of the experiments revealed the following. When the magnetic field strength during preliminary magnetic separation is below 50 kA / m, and when repeated magnetic separation is below 20 kA / m, the yield of iron concentrate is sharply reduced.

 When the magnetic field strength during preliminary magnetic separation is higher than 90 kA / m, and when repeated magnetic separation is higher than 70 kA / m, the iron content in the concentrate sharply decreases.

 When grinding the magnetic fraction extracted during preliminary magnetic separation below the particle class of 0.063 mm, the yield of iron concentrate also sharply decreases, and when grinding to a particle class of more than 0.2 mm, the iron content in the concentrate sharply decreases.

 The summary results of experiments with different modes of preliminary magnetic separation are shown in Table 1, repeated magnetic separation in Table 2, and grinding of the magnetic fraction extracted during the preliminary magnetic separation in Table 3.

 The method is as follows.

 The ash obtained at the thermal power plant from burning coal from the Ekibazstuz opencast mine, with an iron content of 15% in the form of pulp, was cleaned of debris and large sintered ash particles by classification according to the 1-3 mm class. After this, the pulp was thickened to a solid content of at least 200 g / l to ensure the efficient operation of existing equipment during subsequent operations.

 Then the pulp was subjected to wet magnetic separation at a magnetic field strength of 60 kA / m, resulting in a magnetic concentrate with an iron content of 46.3%. After its regrinding to a class of 0.15 mm, repeated magnetic separation was carried out at a magnetic field strength of 30 kA / m.

 As a result of these actions, a concentrate was obtained with an iron content of 53.5%, while the extraction of iron in the concentrate was 75%, and the yield of concentrate was 23%.

Claims (1)

 A method of producing iron concentrate, including preliminary magnetic separation of ash from fuel combustion, grinding of the magnetic fraction and re-magnetic separation, characterized in that the pulp of ash from fuel combustion is first obtained, after which the pulp is subjected to preliminary magnetic separation at a magnetic field of 50 to 90 kA / m, the obtained magnetic fraction is crushed to a particle class of 0.2 - 0.063 mm and subjected to repeated magnetic separation at a magnetic field strength of 20 - 70 kA / m.

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