RU2324653C2 - Method of bertrandite-phenacite-fluorite concentrate processing - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of bertrandite-phenacite-fluorite concentrate processing includes the following stages: activation of concentrate, sulphatization of activated product, water leaching of sulphatizated material, separation of the pulp to obtain beryllium sulphate and precipitate, precipitation of beryllium hydroxide from beryllium sulphate solution. Activation of bertrandite-phenacite-fluorite concentrate is performed by milling to the particle size less than 9 mcm, sulphatization of the milled product is performed by 93% sulphuric acid at 250÷300°C.

EFFECT: invention provides recycling of fluorine of the concentrate; reduction of the number of technological operations and reduction of waste cake.

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Description

The invention relates to the metallurgy of beryllium, in particular to the processing of beryllium-containing ore concentrates to beryllium hydroxide.

Known sulfate method for the extraction of beryllium from beryl concentrate, adopted as an analogue [see Everest D. Chemistry of Beryllium. M .: Chemistry, 1968. P.123-124], in which the chemical activity of the beryl concentrate is increased by melting it at high temperature without the addition of fluxes, followed by water granulation of the melt, and the obtained granulate is subjected to heat treatment. The heat-treated granulate is treated with sulfuric acid and leached with water. As a result of this operation, a solution of beryllium sulfates, aluminum and various impurities contained in the beryl concentrate is obtained, and an insoluble residue of filtered silica. Melting of beryl concentrate and heat treatment of its granulate does not require additional consumption of chemicals. This method of opening the concentrate is based solely on crystallographic changes in the molecular structure of beryl resulting from its melting at 1650 ° C and rapid cooling of the melt at a rate of more than 750 ° C / s [see Everest D. Chemistry of Beryllium. M .: Chemistry, 1968. P.124]. Moreover, due to the high cooling rate, the structure of the liquid melt is fixed in the granulate, i.e. glass structure. Such material is opened by sulfuric acid only 50 ÷ 60 wt.%. However, in the process of subsequent heat treatment of the granulate at 950 ° C, its structure is transformed so that beryllium is released in solid solution in the form of modified phenakite microcrystals, which are quite soluble in sulfuric acid. The usual practical yield of beryllium from a concentrate into a sulfate solution by this technology is on average about 91 wt.%. [cm. White D., Burke J. Beryllium. M .: IL, 1960. S. 73].

In the case when the condition for the cooling rate of the melt is not fulfilled in the granulation operation (cooling rate less than 750 ° C / s), beryllium is released in solid solution in the form of crystallized beryllium oxide, which is subsequently practically not opened by sulfuric acid. In practice, due to the limited thermal conductivity of the melt, this phenomenon occurs if the size of the drops of melt falling into the water exceeds 0.5 inches. Therefore, the melt granules with sizes exceeding 12 mm are screened out and sent for re-melting [see White D., Burke J. Beryllium. M .: IL, 1960. S. 74]. Significant disadvantages of the analogue method are [see Everest D. Chemistry of Beryllium. M .: Chemistry, 1968. P.123]:

- low extraction of beryllium in the sulfate solution and, accordingly, high losses of beryllium with waste;

- high energy consumption, since the processes of concentrate melting, heat treatment of the granulate and its sulfation occur at high temperatures - 1650 ° C, 950 ° C, 300 ° C, respectively;

- the need for turnover for re-smelting of granulate with a particle size of more than 12 mm in an amount up to 15% of its total mass.

Closest to the claimed invention in terms of similar features is a method for the joint processing of bertrandite-phenakite-fluorite and beryl concentrates with a beryllium content in them of from ~ 2.1 wt.% To ~ 4.2 wt.%, Based on melting a mixture of these concentrates with soda [see Zhurkova Z.A., Matyasova V.E., Matyasov N.G., Samoilov V.I. The method of extraction of beryllium from beryllium-containing concentrates, and.with. 2107742. 1996. IPC С22В 35/00, С01F 3/00]. According to this method adopted as a prototype, the high chemical activity of the concentrates is achieved by concentrating the concentrates to obtain a mass ratio of SiO ₂ : CaO in their mixture of 1.4, sodium carbonate is added to the concentrate mixture to obtain a mass ratio of SiO ₂ : (CaO + Na ₂ O) in the mixture, equal to 1.1 ÷ 1.3 (chemical activation). The prepared mixture is melted, the melt is granulated in water, the granulate is wet milled to a particle size of less than 150 microns, the resulting water-granulate pulp is concentrated and it is sulfated with sulfuric acid at 120 ° C. Next, beryllium sulfate is leached from the sulfate mass with water. The described method for the joint processing of beryllium concentrates provides the extraction of beryllium from granulate into a sulfate solution at 97 ÷ 99 wt.%. The specified method for the joint processing of bertrandite-phenakite-fluorite and beryl concentrates is not without drawbacks, because:

- does not provide for the disposal of a valuable component of bertrandite-phenakite-fluorite concentrate - fluorine. Therefore, by the method, almost all the fluorine contained in the initial charge is removed together with beryllium in a sulfate solution, which leads to the production of a fluorine-rich solution of beryllium sulfate and further reduces the completeness of precipitation of beryllium from this solution in the form of beryllium hydroxide.

- according to this method, a large amount of dump cake is formed;

- requires 5 expensive technological operations at the stage of its preparation for sulfuric acid opening (blending of bertrandite-phenakite-fluorite concentrate with beryl concentrate and soda ash in a predetermined ratio, smelting the mixture, granulating the melt, grinding the granulate, preparing the water pulp of the crushed granulate T with a predetermined ratio : G).

The problem to which the claimed invention is directed is to develop a method for processing bertrandite-phenakite-fluorite concentrate, which, along with high extraction of beryllium into water-soluble sulfate and hydroxide, utilizes the fluorine contained in the concentrate, reduces the volume of dump cake, and reduces the number of technological operations.

A method for processing bertrandite-phenakite-fluorite concentrates is proposed, which includes the stages of activation of concentrates, sulfatization of the activated product, water leaching of the sulfated material, separation of the leaching pulp into a solution of beryllium sulfate and sediment, precipitation of beryllium hydroxide from a solution of beryllium sulfate, according to the proposed method, fen-actranite-fert-bert fluorite concentrate by grinding it to a particle size of less than 9 microns, and sulphatization of the crushed product is carried out with 93% sulfuric acid at a temperature of 250 ÷ 300 ° C.

According to the claimed method, in the process of one-step activation of bertrandite-phenakite-fluorite concentrate by grinding it, the crystal lattices are destroyed and the specific surface area of the minerals contained in it (mechanical activation of minerals) is increased, which increases their chemical activity and further enables the deep opening of the concentrate thus activated 93% sulfuric acid at a temperature of 250 ÷ 300 ° C, with the formation of water-soluble beryllium sulfate and gaseous fluoride cre Nia. Gaseous silicon fluoride is removed from the reaction zone and disposed of in a separate apparatus in the form of hydrofluoric acid. Due to defluorination of the concentrate during its opening with sulfuric acid during the leaching operation, a solution of beryllium sulfate with a low fluorine content is obtained, which further improves the completeness of the deposition of beryllium from a sulfate solution into beryllium hydroxide. Since the inventive method does not use fluxes, the total mass of liquid and solid waste is reduced. Energy costs during the implementation of the method are also reduced, because there is no energy-intensive operation of concentrate smelting, and the energy consumption for grinding the concentrate is negligible.

Implementation example

Samples of bertrandite-phenakite-fluorite concentrate weighing 50 g, containing 2 g of beryllium, were crushed (mechanically activated) in a planetary mill. Dry powdered concentrate was treated with 93% sulfuric acid at the rate of 0.8 ml of acid per 1 gram of concentrate. The resulting reaction mass was sulfated, keeping the mixture for 30 minutes at a temperature of 250 ÷ 300 ° C. In this case, gaseous silicon fluoride was absorbed in a separate apparatus to obtain hydrofluoric acid. The sulfated product was leached with water at T: W = 1: 5 (in the initial concentrate) at a temperature of 90 ÷ 100 ° C for 20 minutes. Sulfuric acid pulp from the leaching operation was neutralized with an ammonia solution to a pH of ~ 3.5 and filtered. The cake obtained after filtration was subjected to double filter-repulpation washing from beryllium sulfate at Т: W = 1: 7 (in the initial concentrate) and a temperature of 90 ÷ 100 ° С for 15 min. By the residual beryllium content in the cake, the completeness of beryllium extraction was determined. Beryllium crude hydroxide was precipitated from the filtrate (sulfate solution) with an ammonia solution, from which, after dissolution in alkali and hydrolysis of sodium beryllate, the final processing product, technical beryllium hydroxide, was obtained.

For comparison with the claimed invention received sulfated product by the prototype method. For this purpose, a mixture of bertrandite-phenakite-fluorite and beryl concentrates was prepared, the amount of each of which was determined on the basis of obtaining the necessary mass ratio in the mixture of silicon and calcium concentrates contained in the composition in terms of SiO ₂ : CaO oxides equal to 1.4 and containing weighed 2 g of beryllium. Sodium carbonate was added to the prepared concentrate mixture based on the calculation of the mass ratio in the mixture between silicon, calcium and sodium in terms of SiO ₂ : (CaO + Na ₂ O) oxides equal to 1.1–1.3.

Then, the resulting mixture is loaded into a graphite crucible and melted at a temperature of ~ 1360 ° C. The melt was poured into cold water, the obtained granules were dried and crushed. The crushed melt was pulped in water at a ratio of T: W = 1: 1. 93% sulfuric acid was added to the resulting pulp at the rate of 0.8 ml of acid per 1 gram of granulate, the resulting reaction mass was kept for 5 min at a temperature of 120 ° C. The processing of the thus obtained sulfated product was carried out similarly to the processing of the sulfated product according to the claimed invention.

Table 1 shows the characteristics of the concentrates used in the work, and table 2 shows the results of the method according to the claimed invention and, for comparison, the prototype method.

Table 1 The chemical composition of beryllium concentrates Name of concentrate The content of the components. wt.% Be SiO ₂ Cao F Al ₂ O ₃ , FeO, Fe ₂ O ₃ , etc. Bertrandite-phenakite-fluorite four 25 thirty 10 31 Beryl 2 55 one one 41 Note: the size of the concentrates is from 70 to 150 microns

From the data given in table 2, it follows that when implementing the method according to the claimed invention in examples 3-5, the extraction of beryllium from mechanically activated concentrate in a sulfate solution is 98-99 wt.%, And the extraction of fluorine in the gas phase is 88-90 wt. .%, respectively. Moreover, in examples 3-5, the size of the crushed concentrate is less than 9 microns.

Inadequate grinding of the concentrate leads to a decrease in the extraction of beryllium and fluorine from the concentrate to 96 wt.% And to 85 wt.%, Respectively (see example 2, when the size of the crushed concentrate is 12 μm) and up to 80 wt.%. (see example 1, without grinding, the fineness of the concentrate is - 85 microns).

In examples 6-7, the results of opening the charge according to the prototype method are presented, in which the extraction of beryllium from the melt is 97 ÷ 99 wt.% While the fluorine is removed from the melt by only 6 wt.%.

Due to a more complete defluorination of raw materials in the inventive method (approx. 3-5, table 2), in comparison with the prototype method (approx. 6,7, table 2), a deeper deposition of beryllium from solution into rough beryllium hydroxide is achieved 99.5 wt.% Against 97.0-97.4 wt.%.

Thus, when processing bertrandite-phenakite-fluorite concentrate, the inventive method, in comparison with the prototype method, allows beryllium to be extracted into the sulfate solution no less efficiently and provides an increase in the removal of fluorine from granulate to 88 ÷ 90 wt.% With the possibility of utilizing the latter in the form of valuable commodity product - hydrofluoric acid. The number of dump cakes decreases by 10 ÷ 18 wt.%. In addition, in the claimed method, in comparison with the prototype method, such technical results are achieved as a 20-30% reduction in energy costs, a 15-30% reduction in the weight of the feedstock and reagents, a 2-2.5% increase in the hydroxide deposition rate beryllium from a sulfate solution and a decrease in the volume of waste water to 20%.

Claims (1)

A method for processing bertrandite-phenakite-fluorite concentrates, which includes the steps of activating the concentrates, sulfating the activated product, water leaching of the sulfated material, separating the leaching pulp into a solution of beryllium sulfate and a precipitate, precipitating beryllium hydroxide from a solution of beryllium sulfate, characterized in that they activate fen-nitrite fluorite concentrate by grinding it to a particle size of less than 9 microns, and sulfatization of the crushed product is carried out with 93% sulfuric acid at The temperature of 250 ÷ 300 ° C.