RU2205235C1 - Method for producing fluorspar briquettes - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: method involves mixing small-grain concentrate with combined binder; pressing resultant mixture at normal (room) temperature and strengthening briquettes by holding them under natural conditions. Combined binder comprises mixture of slaked lime and molasses with solid content of 58-70%, said mixture being introduced in an amount of 5-11 wt% of concentrate at slaked lime and molasses ratio of 1:1 on the basis of dry weight. Molasses is preliminarily heated to 50 C and slaked lime is supplied for mixing in dry state. Specific pressure is 180-220 t/sq.m. Method may be used for preparing ores and concentrates for melting in the process of manufacture of fluorspar briquettes and allows said briquettes to be produced without necessity of burning process. Strength of said briquettes meets requirement accepted in metallurgy and sufficient for transportation thereof without damage, and possesses improved moisture resistance allowing said briquettes to be stored in open air. EFFECT: increased efficiency and enhanced reliability in operation. 4 cl, 1 tbl

Description

 The invention relates to metallurgy, in particular to methods for preparing ores and concentrates for smelting, and can be used in enterprises producing fluorspar briquettes.

 Fluorspar (fluorite) is added to the slag in the steelmaking converter to give the slag greater fluidity. In the past, it was added in the form of lump fluorspar. Recently, however, coarse-grained fluorspar has become scarce material. The supply of fine-grained fluorspar to the converter is technically difficult to implement, since it is carried out from the converter with a gas stream, as a result of which its utilization is greatly reduced.

For the possibility of using finely ground concentrates in metallurgical processes, their special preparation is required - agglomeration, pelletizing, briquetting. A known method of producing pellets of fluorspar, comprising mixing the concentrate with a binder and firing the pellets at 950-980 ^o With, and as a binder use dust from aluminum production [ed. USSR 979512, class C 22 V 1/243, 1982].

 The main disadvantage of this method is the high operating costs of firing and low strength pellets. In addition, firing leads to air pollution by gases and dust.

 The closest in technical essence and the achieved result to the proposed one is a method of producing briquettes of fluorspar, comprising mixing fine-grained concentrate with a combined binder, which is used as a mixture of lime-fluff fluff and molasses, taken on the basis of dry weight in a ratio of 1: 1, the subsequent pressing of the mixture at normal (room) temperature and hardening of briquettes by aging in natural conditions [Ravich B. M. Briquetting of ores. - M .: Nedra, 1982, p. 63-64].

 The disadvantage of this method is the lack of strength of the briquettes in conditions of prolonged transportation and multiple overloads.

 The inventive method allows to obtain briquettes of fluorspar of such strength that they do not fall apart during transportation loads, and have good resistance to moisture when stored in the open.

The specified technical result is achieved by the fact that in the known method for producing briquettes of fluorspar, comprising mixing fine-grained concentrate with a combined binder, which is used as a mixture of lime-fluff fluff and molasses, taken on the basis of dry weight in a ratio of 1: 1, the subsequent pressing of the mixture at normal (room) temperature and hardening the briquettes by exposure to natural conditions, according to the invention, molasses is fed to a mixing heated to 50 ^o C condition, and containing ue solid therein is 58-70%. A mixture of lime-fluff and molasses is introduced in an amount of 5-11 wt.% Concentrate, lime fluff is fed to the mixture in dry form, and the formation of the briquette is carried out with a specific pressing pressure of 180-220 t / m ² .

 The invention consists in the following.

 Separate use of lime-fluff fluff and molasses (molasses) as binders for fluorspar is known. However, their joint use in this context leads to more satisfactory results.

 Lime is an astringent consisting primarily of calcium oxide and magnesium oxide. The process of natural hardening of lime, turning it into a cementitious material, consists in the crystallization of calcium oxide hydrate and its carbonization with atmospheric carbon dioxide. The latter enters into a chemical compound with calcium hydroxide, forming calcium carbonate. The process of natural carbonization (in air) proceeds slowly due to the low concentration (about 0.04%) of carbon dioxide in the air and the formation of a crust of calcium carbonate on the hardening briquette, which prevents the diffusion of carbon dioxide into its inner part. The carbonization process can be accelerated by the introduction of surfactant catalysts into the batch for briquetting.

 Melassa (molasses) - a sugar production waste - is used as part of a combined binder as a cementing or strengthening additive for briquetting ore raw materials. The essence of molasses as a catalyst is to accelerate the formation of calcium carbonates due to the formation of an intermediate colloidal complex with saccharide.

 The initial strength obtained in accordance with the invention of the briquettes is high enough and allows you to abandon the long drying period. This eliminates interim storage. The resulting briquettes can be satisfactorily stored in the open air, as they have good resistance to moisture.

 It was experimentally established that only compliance with the entire set of process conditions indicated above allows obtaining feldspar briquettes having mechanical and physico-chemical properties that meet the requirements of fluorspar according to GOST 7618-70 for use in the metallurgical industry.

So, it was experimentally found that the solids content in the molasses fed to mixing is 58-70%, since it is at these values, and also while heating it to 50 ^o , that the optimum viscosity is achieved, which is a function of the percentage of solid particles (specific weight) and temperature, which increases the adhesive ability of the binder and leads to the best enveloping of the particles of the mixture supplied for mixing, and increasing the adhesion between them creates a solid briquette frame during its formation.

 It was also found that the amount of each of the components of the combined binder supplied for mixing (5-11% by weight of the concentrate) and their ratio to each other based on dry weight (1: 1) are optimal in terms of achieving high quality of the target product.

 With a binder consumption of more than 11% by weight of the concentrate, the briquettes become more moisture resistant, but the cost of briquetting increases. When using less than 5% binders, briquettes become less moisture resistant and less durable.

The established range of specific pressure during pressing (180-220 t / m ² ) allows to obtain briquettes of the required strength. At a pressure of less than 180 t / m ^2, the briquettes just obtained do not have the strength necessary for their further processing (crumble), and a pressure of more than 220 t / m is impractical from the point of view of the cost of the process. In addition, cracks form on the surface of the briquettes.

 Lime-fluff is served for mixing in a dry form, since feeding it in the form of a solution increases the moisture content of the briquettes, which leads to a sharp decrease in their strength.

 The following is an example confirming the possibility of implementing the claimed invention.

 Example.

The mixture fed to the mixer consists of a fluorite concentrate with a grain size of 90% class - 44 microns with a fluorite content of 83%, and a combined binder: lime-fluff and molasses, which are in a 1: 1 ratio and served in an amount of 5% by weight of the concentrate. The initial concentrate contains moisture of 0.0%, fluffy lime is supplied in dry form, and the solid content in molasses is 70%. When the dosage of molasses is heated to 50 ^o C and enters through pipes from the consumable tub and dispenser to the mixer. The mixer thoroughly mixes the mixture for 15 minutes and feeds it to pressing. The press operates at a pressure of 220 t / m ² . Drying of the obtained briquettes after pressing occurs naturally when they are stored.

 The results of the influence of the amount of binder and agglomeration conditions on the physicomechanical properties of briquettes are given in the table. Variables evaluated over a series of experiments are crushing strength and exposure to water. The briquette crushing force is given immediately after manufacture, after 3 hours, 24 hours, and 48 hours. Under the influence of water is meant the amount of moisture (wt.%) That absorbs the briquette when it is kept in water for an hour.

The table shows that the best briquettes in terms of mechanical strength and water resistance are obtained by introducing a combined binder consisting of a mixture of lime-fluff and molasses, in an amount of 5-11 wt.% Concentrate, with a solids content of 58-70% in molasses and forming a briquette with a specific pressing pressure of 180-220 t / m ² .

 Thus, the inventive method allows to obtain without firing durable moisture-resistant briquettes of fluorspar, corresponding to the requirements for ore briquettes for the needs of non-ferrous and ferrous metallurgy.

Claims (4)

1. A method of producing briquettes of fluorspar, comprising mixing fine-grained concentrate with a combined binder, which is used as a mixture of lime-fluff fluff and molasses, taken on the basis of dry weight in a ratio of 1: 1, the subsequent pressing of the mixture at normal temperature and hardening the briquettes by exposure to in vivo, characterized in that the molasses is served for mixing in a state heated to 50 ^{° C.} , and the solid content in it is 58-70%.  2. The method according to p. 1, characterized in that the mixture of lime-fluff and molasses is introduced in an amount of 5-11 wt. % concentrate.  3. The method according to p. 1, characterized in that the lime fluff is served for mixing in a dry form. 4. The method according to p. 1, characterized in that the briquette is formed with a specific pressing pressure of 180-220 t / m ² .

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