SU812845A1 - Method of pelletizing fluorite concentrate - Google Patents

Description

(54) METHOD FOR DIVING FLUORITE CONCENTRATE

This invention relates to the steel industry; in particular, to pretreatment of ores, and can be. used for agglomeration of fluorite concentrate. Methods are known for the agglomeration of finely dispersed fluorite concentrate, where, along with roasting methods, non-calcined ones are also used, in which silicon-containing substances (cement, bentonite, liquid glass, etc.) are used as a binder material, fluorite concentrate used in ferrous metallurgy and for the production of electrofused fluxes, predominantly a finely dispersed fraction (less than 1 mm) is obtained, which significantly reduces its efficiency due to large losses. when the material is fed into the metallurgical unit. Thus, in the production of welding fluxes and electroslag remelting (ESR), the utilization rate of fine fluorite concentrate is 1.2–2.4 times higher than required, which significantly reduces the technical and economic indicators of flux production using such a material. Taking into account the deficiency and high cost of fluorite, the need for its agglomeration before smelting is not in doubt. However, these methods have a number of disadvantages, the main of which is the high content of silica in binding materials (SiO .; 3%), which is highly undesirable in the production of a number of fluxes and, in particular, ESR fluxes, where silica is a harmful impurity (below 3%). The closest to the invention according to the technical nature is a method of sintering fluorite concentrate using 0.1-0.3% sulphonirr pulp as a binder and subsequent roasting up to 900 ° C at a heating rate of 4.5 degrees / min 12. Disadvantages of the known method are relatively low mechanical strength, which leads to the scattering of part of the pellets (up to 15%), as well as the presence in connection of the i-containing material, which is undesirable in the production of fluorite pellets for fluxes of ESR, where sulfur is a harmful impurity. Temperature conditions are determined by the nature of the binder material, which has the ability

ignite at high heating rate of the pellets. This reduces the productivity of the process.

The purpose of the invention is to obtain high-strength pellets with a silica content of not more than 3%,

This goal is achieved by the use of polyacrylamide and sludge from the production of electrofused flux in an amount of 0.02-1.0% and 0.5-5.0%, respectively, based on the weight of fluorite. concentrate, and strengthening calcination is carried out at a rate of 70-80 degrees / min to a temperature of lOOO-llOO c. In addition, polyacrylamide is used in the form of 0.81, 2% aqueous solution in an amount of 0.05-0.8% by weight of fluorite concentrate.

The polyacrylamide used as binder is a hydrolyzed product obtained by the polymerization of acrylic or methacrylic acid. The sludge generated during the production of electrofused fluxes has a composition,%: CaFj 25-60 /

sao AijO e-ie; IGO 5-9;

SiOz. 2-3.

The composition of fluorite concentrate brand FF-92 includes,%: CaF2 91.0, .SiOu2.2; FeO 0.26; P 0.038; S 0.050

The concentration of an aqueous solution of polyacrylamide (PAA) may vary between 0.8-1.2%. The lower concentration limit is due to the preparation of a mixture for the agglomeration of the concentrate, which allows it to be rounded. A lower concentration of the aqueous solution is not desirable because of the formation of a liquid mixture that makes it difficult to coat and also requires additional moisture during thermal heating, which increases the heating time. Higher concentrations do not allow a sufficiently wettable {p mixture, which also complicates the coating process.

Given in table. 3 temperature range is due to the need to test the physico-mechanical: characteristics of the pellets at

The number of drops from the height of 0.3 m to the destruction

lower temperatures, which are observed during the transportation or supply of pellets in the smelting units. In the presence of certain strength properties even of non-conforming (since they did not undergo heat-strengthening roasting) pellets (number of drops 3, crushing effort up to 30 kg / pellet) high strength properties of finished pellets of the necks made according to the proposed technology at low positive and even negative temperatures remain what happens with industrial use of pellets in the winter.

 Three stages of heating due to

the selected heating rate of pellets is 70-80 degrees / min and the time of thermo-direct roasting for 30-40 minutes, since these parameters ensure the passage of pellets through the following necessary technological operations of temperature heating: removal of moisture, hardening of the fluorite plastic mass, formation of a carbon-containing frame, strengthening This firing, which, ultimately, allows to obtain high-strength characteristics of the pellets. If the -heating is performed by other parameters, then

Q the specified heating steps will not occur, with the required technological feasibility, which, ultimately, will affect the physical and mechanical properties of the pellets.

with Example. The fluorite concentrate is subjected to pelleting on a pelletizer together with bonding materials. The rotational speed of the pelletizer is 24 rpm. Polyacrylate amide is well soluble in water,

Therefore, it is possible to determine the optimal concentration of PAA and, consequently, its consumption, using aqueous solutions of different concentrations. PAA consumption affects mechanical

5 properties of pellets. The effect of N1-Re PAA consumption on the strength of raw pellets with a diameter of 10-20 mm is presented in Table. one.

Table

From tab. 1, it follows that the optimal concentration of the aqueous solution of PAA should be 0.2-10% or, in terms of PAA, on the dry weight of the pellet (fluoride concentrate) 0.021, 0% by weight of fluorite. Below and above these limits are mechanical properties.

The number of triggers from a height of 0.3 m to destruction

The hardening of the pellets during natural drying is negligible. Therefore, in order to obtain high-strength pellets, strengthening pellets are fired. In this case, it is possible to distinguish three stages of heating: drying (300 ° C) - moisture is removed, heating (300-900 0 - hardening of the plastic mass of fluorite occurs with partial formation of coal 12

50

thirty

The proposed method of obtaining high strength grades provides a high yield of pellets, not lower than 92-96%, in the known method this value is 85-90%.

The chemical composition of the pellets obtained by the proposed method, the following%:

CaF: a 91.5-92.3; SiOg 1.8-2.2; FeO 0.24-0.26, - S 0.050; P 0.038; C 0.020, 05.

The invention can be implemented without the use of cuttings from the production of coils deteriorating. Similarly, the effect of the slurry consumption of the production of electrofused flux on the mechanical properties is investigated. As can be seen from Table 2, the optimum consumption is 0.5-5% by weight of the fluorite concentrate.

table 2

a rode-containing framework controlling the pellet and firing (1000-1100 ° C) for strengthening the pellets. The heating rate is 70-80 degrees / min, the calcining and cooling time of the pellets is 30-40 min. The selected heating mode provides high mechanical properties of pellets with an optimal content of binder, as can be seen from the table. 3

Table 3

13

15

12

ten

ten

65

70

60

60 th 50

Claims (2)

electrowelled fluxes, which allows to obtain pellets with a silica content of up to 2.5%. To do this, use a 1.0% aqueous solution of polyacrylamide in the amount of 0.05-0.8% by weight of fluorite concentrate. Such concentration and consumption of PAA are, as can be seen from table. 1, optimal, provide high-strength pellets, although the loss of production of pellets in this embodiment is up to 10%. The technical advantages of the invention are the production of pellets with a low content of harmful impurities and high mechanical strength using the equipment available at the enterprises, the lack of binding materials. Claim 1. A method for sintering fluorite concentrate, which includes spraying with a bonding material and the subsequent strengthening roasting, is necessary in order to obtain high-strength pellets with a content of silica, not more than 3%; polyacrylamide and sludge from the production of electrofused fluxes in an amount of 0.02-1.0% are used as a binder. and 0.5-5.0%, respectively, based on the weight of fluorite concentrate, and heating up to the burning temperature of 1000-1100 s is carried out at a speed of 70 - 80 degrees / min. 2. The method according to claim 1, about. Tl and h and y and so that, in order to reduce the silica content in the pellets to 2.5%, polyacrylamide is used as O, 8-1.2% 0.05-0.8% by weight of fluorite concentrate. Sources of information taken into account during the examination 1. Korotich V.I. and etc. . Development and research of the technology of obtaining pellets from flotation fluorite concentrates. Preparation and restoration of ores, vol. 1, 1970, 2. German patent 1153393, (Cl, 18a, 1/26, 1970,