RU2266967C1 - Method of preparation of fluxes for production of fluxed agglomerate - Google Patents

Abstract

FIELD: metallurgy; preliminary treatment of ores; production of fluxed agglomerates for melting cast iron.

SUBSTANCE: proposed method includes preparation of limestone and dolomite including separate crushing, sorting of each kind of flux and grinding to required size before delivery to agglomeration charge. Amount of each kind of flux is determined depending on preset content of magnesium oxide by the following formulae: Q_d-m=[((MgO)_fl-(MgO)_l-s/(((MgO)_d-m-(MgO)_l-s)] M_mp, where Q_d-m is amount of dolomite, t; (MgO)_d-m is content of magnesium oxide in dolomite, %; (MgO)_l-s is content of magnesium oxide in limestone, %; (MgO)_fl is preset content of magnesium oxide in flux, %; M_mp is cargo capacity of transport facility; Q_l-s=M_mp-Q_d-m, where Q_l-s is amount of limestone, t. Proposed method makes it possible to obtain mixture of fluxes at preset content of MgO and to reduce variation in basicity and content of MgO in fluxed agglomerate.

EFFECT: enhanced efficiency; reduced variation in basicity and content of magnesium oxide in fluxed agglomerate.

1 tbl, 1 ex

Description

The invention relates to metallurgy, in particular to pre-treatment of ores, and can be used for the production of fluxed sinter used for smelting cast iron.

Known methods of preparing fluxes when introducing them into the sintering mixture, including partial and complete averaging of them using dosage and layer-by-layer stacking in specially equipped warehouses (E.F. 176-181, 230-231; The use of averaging stacks and sintering technology at the sinter factory of the Thyssen company in Schwelgern. Ferrous metals. 1983, No. 14, p. 39-40).

To implement this method, it is necessary to build special warehouses and purchase expensive equipment.

The closest analogue to the claimed method is a method of preparing fluxes for producing fluxed agglomerate, including separate crushing and sorting of each type of flux (limestone and dolomite), storage in bunkers, loading in separate vehicles, transportation to sinter plants, where after grinding to a certain coarseness of fluxes served in sinter charge (A.S. Sladkov. Preparation of fluxes for blast-furnace smelting. M: Metallurgy, 1966, p. 169-171).

The disadvantage of this method is the difficulty of obtaining a predetermined limit of the content of magnesium oxide MgO in the fluxes with the separate supply of limestone and dolomite to the sinter mixture.

The proposed technical solution will allow, without large material costs, to obtain a flux mixture with predetermined limits of the MgO content, to reduce fluctuations in basicity and MgO content in the fluxed agglomerate.

The technical result is ensured by the fact that in the proposed method, which includes separate crushing, sorting of each type of flux and grinding to the required size before feeding into the sinter mixture / fluxes after sorting are mixed, the amount of each type of flux is determined depending on the given content of magnesium oxide according to the formulas:

where Q _d-t - the amount of dolomite, t;

(MgO) _d-t - the content of magnesium oxide in dolomite,%;

(MgO) _Izv-k - the content of magnesium oxide in limestone,%;

(MgO) _fl. - a given content of magnesium oxide in the flux,%;

M _tr - vehicle carrying capacity.

where Q _iz-k - the amount of limestone, t

Additional mixing, which is carried out after sorting the fluxes by size, in the process of transferring them to the sinter plant, for example, on conveyors when loading into vehicles, mainly wagons, when both types of fluxes are fed alternately to one wagon, i.e. dolomite and limestone, reduces the agglomerate fluctuations in the content of magnesium oxide and basicity.

Using the proposed dependences to calculate the amount of dolomite and limestone allows you to get a mixture of fluxes, the fluctuations of the MgO content in which do not exceed ± 0.5% of the calculated value, which allows you to get the fluxed agglomerate even in basicity and MgO content.

An example implementation of the method. Limestone and dolomite up to 1000 mm in size are delivered to the crushing and screening plant (DSF), which are crushed into separate fractions from 0 to 80 mm in size, sorted into three fractions (from 40 to 80 mm, from 20 to 40 mm, from 0 up to 20 mm). A fraction from 0 to 20 mm is stored in a limestone bin with a capacity of 1250 tons, which has five vibratory feeders at the discharge, and in a dolomite bin with a capacity of 500 tons with two vibratory feeders. The MgO content was determined before their storage in the bunker and amounted to 3.5% in limestone and 17.2% in dolomite.

The predetermined MgO content in the raw flux is 5.2%. The calculation of the amount of dolomite and limestone is carried out according to the formulas (1, 2):

where 70 - carrying capacity of the vehicle - railway carriage, t

Mixing dolomite with limestone is carried out in the process of transporting fluxes to the sinter plant, on conveyors transporting fluxes to cars, and directly in cars by alternately feeding dolomite and limestone.

For the dosage of limestone and dolomite, automatic scales of the 1954 AB 10-630 type are installed on the DSF conveyors, the readings of the counters of which are displayed on the console of the DSF shipment operator. In addition, a multifunctional controller “Remicont-130” is installed on the remote control, which allows you to set a certain amount of material in each car.

The prepared flux mixture is sent to sinter plants, where it is discharged from the wagons to the receiving hoppers and is conveyed by a belt conveyor to hammer crushers for grinding to a particle size of 0 to 3 mm and transported to the bunker of the charge compartment.

The results of the experiments are shown in the table.

Fluctuations in the chemical composition of fluxes, MgO content, and basicity in fluxed sinter with different methods of preparing fluxes Limestone Averaging Technology Month Evenness in the content of MgO in fluxes,% Evenness in the MgO content in the agglomerate,
% Evenness in basicity in the agglomerate,
% RMS Fluxing agent Fluxed agglomerate MgO content MgO content Basicity Analogue February 73,4 75.1 88.6 0.764 0.211 0,088 March 76,2 88.3 92.1 0.643 0.169 0,062 April 78,2 92.3 98.3 0.521 0.158 0,053 Average 75.9 85,2 93.0 0.642 0.279 0,068 The inventive method May 96.7 88.0 94.2 0.422 0.168 0,048 June 97.2 89.3 96.4 0.386 0.147 0,036 July 98.5 96.7 99.3 0.291 0.140 0,025 Average 97.4 91.0 96.6 0.366 0.151 0,036 Changes +21.5 +5.8 +5.3 -0.276 -0.128 -0.032

Claims (1)

A method of preparing fluxes for the production of fluxed agglomerate, namely limestone and dolomite, including separate crushing, sorting of each type of flux and grinding to the required size before feeding into the sinter mixture, characterized in that after sorting the fluxes are mixed, and the amount of each type of flux is determined depending from a given content of magnesium oxide according to the formulas

where Q _dm is the amount of dolomite, t; (MgO) _dm — content of magnesium oxide in dolomite,%; (MgO) _Izv-k - the content of magnesium oxide in limestone,%; (MgO) _fl. - a given content of magnesium oxide in the flux,%; M _mp - carrying capacity of the vehicle; Q _cv = M _mp -Q _dm , where Q _iz-k - the amount of limestone, t