SU834163A1 - Method of oxidizing roasting of pyrite-containing materials - Google Patents

Description

(54) METHOD OF OXIDATING FIRING OF PYRITE-CONTAINING MATERIALS, which is why the process can be carried out in the case of incomplete oxidation of sulfur released during thermal dissociation of pyrite. The lower limit of the amount of oxygen supplied to the layer is determined by the thermal balance of the installation and must ensure that the temperature of the layer is below 680 ° C. In the absence of heat loss, the oxygen consumption can be reduced to 0.08 nm per kilogram of pyrite. At temperatures above 780 ° C, the pyrite dissociation rate is large and the particle dissociation time can be much less than the residence time of particles in the layer, which leads to partial oxidation of pyrrhotite. Thus, to obtain pyrrhotite containing less than 4: -5% of oxidized iron, it is necessary to carry out the process at 680-780 ° C. Since the process can be carried out with the oxygen consumption in the blast less than necessary for complete oxidation of elemental sulfur, i.e. with an excess of pyrite in the bed relative to the oxygen supplied, oxygen is used, completely, and the gases are concentrated on the content of sulfur dioxide. In addition, part of the sulfur (up to 50-60% of that extracted in ra3j) can be obtained as elemental.

concentrate loading speed.

The results of the experiments are assessed by chemical and mineralogical analysis of the calcine products and their yield.

The table shows the conditions of the experiments and their results. The process proceeds without fuel costs and can be carried out in standard fluidized bed furnaces, equipped with hermetic units for the loading of raw materials and discharge of calcine. Example. The method was tested in pilot-scale conditions on a cylindrical-shaped fluidized bed furnace with a working cross-section of 0.33 m2. Pyrite concentrate containing 42.543, 5% iron and 48-50% sulfur after drying to a residual moisture content of less than 1% is fed into the furnace from the hopper using a plate feeder. The calcine is unloaded through a water cooled chute, an intermediate cooler and a water cooled auger. A cold air blast in the amount of 300 is fed into the layer through a hearth equipped with air distribution nozzles with a live (0.7% cross section. Dust removal of gases is carried out sequentially in a cyclone and a dry electrostatic precipitator. The temperature of the layer is adjusted by

315

0.2 o

780

78-80

9-10

a 10-12

58, O-59, O57.0-58,556,5-58.0

33.0-34.034.0-36.035.5-37.0

55.0-57.054.0-55.052.0-54.0

35.0-36.036.0-38.038.0-39.5

17-18

1-2 22.7

The results of mineralogical analysis show that iron in the calcine is 95-98% bound to pyrrhotite and 2-5% to magnetite.

430

500

Oh 145

Oh, 1O

730

680 78-80 78-80

9-10

9-10 10-12 1О-12

17-18

17-18 2-3 3-4

31.0

36.1

The content of oxidized iron in the form of hematite and magnetite in dusts also does not exceed 5%.

Thus, the proposed method allows the thermal dissociation of pyrite-holding materials and a pyrrhotite calcine with a low content of iron oxides.

Claims (1)

Invention Formula The oxidative method. roasting pyrite-containing materials including them Heat treatment in a fluidized bed with the supply of oxidizing oxygen-containing gas to the layer, characterized in that, in order to reduce the cost and simplification of technology, oxidative roasting is carried out with oxygen consumption in the blast of 0.08-0.2 nm per kilogram of pyrite in the feedstock. Sources of information taken into account in the examination 1. Patent of England No. 1226087, cl. From 22 to 1/10, published. 1969.