RU2383637C1 - Charge and method of extracting noble metals out of it - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: charge consists of raw material containing noble metals, slag forming substances for slag production with base of 0.2-0.35 of flux forming elements and silicon as solvent. The method consists in preparing charge, in melting and conditioning the most heat resistant noble material in charge at temperature 50-100°C above temperature of melting. Further charge is cooled and metal phase is separated from slag and flux.

EFFECT: increased extraction of noble metals into metal phase.

2 cl, 2 tbl, 3 ex

Description

The invention relates to ferrous metallurgy, and in particular to the production of noble metals.

The known gravitational method for the extraction of platinum metals from ores of bulk deposits [1, p. 346]. This method does not allow the extraction of platinum metals from primary deposits.

There is also a known method for the extraction of platinum metals from primary deposits. For this, complex enrichment schemes are used, including crushing, enrichment at locks and tables [1, p. 346]. The disadvantage of this method is the complex scheme and the incomplete extraction of precious metals, in addition, these methods are not applicable to all ores.

Known charge for the extraction of platinum and precious metals from raw materials containing slag, ore [1, p. 346], a reducing agent.

There is also a method of extracting platinum metals from sulfide copper-nickel ores [1, p. 346]. The essence of the method is the smelting of copper-Nickel ores in an electric arc furnace. In this case, matte and slag are obtained. The disadvantage of the mixture and its melting method is that part of the noble metals is extracted into matte (65-90%), and part (10-35%) goes back to slag and is lost irrevocably. Noble metals are not recovered from slag.

The closest is the mixture for the extraction of precious metals from raw materials containing precious metals, slag-forming and flux-forming in the form of soda, glass and lime [2].

There is also a method of extracting precious metals into the metal phase during melting, including the preparation of the charge, loading these components of the charge into the furnace, melting, cooling and separating the metal phase from slag and flux [2].

The disadvantage of this mixture and the extraction method is that it is used only for processing scrap electronic equipment. At the same time, scrap is divided into two or more intermediate products and each of them is processed by various and very complex technologies.

The problem solved by the invention is the complete extraction of all precious metals from concentrates, secondary raw materials and scrap into one product - molten silicon, which is a universal solvent for metals. And noble metals can then be extracted from this alloy.

To achieve the technical result provided by the invention, a mixture is used to extract noble metals into the metal phase during melting, consisting of raw materials containing noble metals, slag-forming based on silica and limestone, fluxing and silicon as a solvent, characterized in that it contains chlorides as fluxing and fluorides of alkali and alkaline earth metals, and as slag-forming - slag-forming for the formation of slag with a basicity of 0.2-0.35.

To achieve the technical result provided by the invention, a method is used to extract noble metals into the metal phase during melting, which includes the preparation of a mixture from raw materials containing noble metals, slag-based on silica and limestone, flux-forming and silicon as a solvent, melting and aging, cooling and separation of the metal phase from slag and flux, characterized in that in the preparation of the mixture using slag forming for the formation of slag with a basicity of 0.2-0.35, and as e flyusoobrazuyuschih - chlorides and fluorides of alkali and alkaline earth metals, melting and exposure is carried out at a temperature 50-100 ° C above the melting temperature of the most refractory of the noble metal in the charge.

The essence of the claimed invention lies in the fact that it is proposed to extract precious metals from raw materials by dissolving them in molten silicon. Silicon is a good solvent for metals. For this, a charge is made up of slag-forming substances, flux-forming substances, raw materials from which noble metals are extracted, and the solvent of these metals is silicon. It is known that ore is complex in mineralogical composition. To separate rock minerals from raw materials, it is proposed to transfer them to slag. For this, components are added to the charge, which, when melting the charge, form slag, are easily separated from the molten metal and float to the metal surface. In order to isolate metal and slag from the atmosphere (oxygen and nitrogen), it is proposed to introduce a low-melting flux, or components of a low-melting flux, in particular chlorides and fluorides of alkali and alkaline earth metals, into the composition of the charge. When melting the proposed mixture, three layers of molten mass are formed in height. The lower layer consists of molten silicon with precious metals molten in it. A slag layer forms on the molten metal, which protects the metal from oxidation by atmospheric oxygen and from atmospheric nitrogen, which can react with the metal to form metal nitrides. A flux layer forms above the slag layer. The flux covers the slag and metal from oxidation by atmospheric oxygen and from the interaction of atmospheric nitrogen with metal and slag. Slag is recommended silicate composition (CaO · SiO). It is undesirable to contain iron, manganese, chromium, vanadium and other metals in the slag, which can oxidize platinum and noble metals. As the slag-forming components of the mixture should contain silica and limestone.

Limestone at 900-1000 ° C decomposes into CaO and carbon dioxide CO ₂ , which prevents the oxidation of the metal phase during the melting of the charge. At the same time, CaO reacts with silica to form slag. Thus, the presence of a flux layer and a slag layer above the metal phase eliminates the oxidation of metals and their interaction with nitrogen. Therefore, the loss of precious metals and silicon is prevented. Under these melting conditions, there is no diffusion of platinum metals into the slag. Upon completion of the melting and cooling of the melt, the metal phase is easily separated from the slag. The present invention allows the processing of ores and concentrates of loose and primary deposits, difficult to process sulfide copper-nickel ores, waste and scrap, in particular scrap of electronic equipment and radio engineering.

In the process of melting, isothermal exposure is determined experimentally. The temperature should be 50-100 ° C higher than the melting temperature of the most refractory metal in the charge.

Example 1

To extract platinum metals, gold and silver, iron ore enrichment waste, quartzite, limestone, sodium and potassium chlorides were used. The compositions are presented in table 1.

Table 1 Substance Composition, wt.% The metal content, g / t SiO ₂ Al ₂ O ₃ FeO + Fe ₂ About ₃ Cao MgO MnO SO ₃ Na ₂ O +
K ₂ O Pt Rh Pd Au Ag The waste is enriched -
niya 34.1-39.9 9.8-11 12.8-26.1 11.3-13.7 4.2-5.7 0.3-0.55 1.7-3.2 1.3-3.3 <0.2 <0.2 <0.2 0.08 1,2 Quartzite 97 one 0.5 one 0.4

The initial components, previously dried at a temperature of 115 ° C, are taken in the ratio according to table 2. The mixture was loaded into an alundum glass, placed in a Tamman furnace, heated to 1950 ° C, and kept for one and a half hours. At the end of the isothermal exposure, the furnace was cooled together with the melted charge, the metal phase was separated from the slag and flux and subjected to spectral and chemical analysis. From the results of the analyzes, it follows that palladium ruthenium, rhodium, gold and silver almost completely diffused into silicon. The obtained metal phase can be processed using known technologies [1] with almost complete extraction of platinum metals and gold from iron ore enrichment wastes.

Example 2

In addition, the waste was enriched on the most efficient apparatus for separating fine particles of heavy minerals - the Knelson concentrator. As a result, the composition concentrate was obtained, g / t: Au - 1, Ag - 30, Pt - 2, Pd - 1.5, Rh - 1.

The concentrate was processed by the proposed method. Extraction of platinum metals, gold, silver in silicon amounted to 90-98%.

Example 3

Scrap electronic equipment containing palladium was processed by the proposed method. The recovery of palladium in silicon was 98%.

The technical result from the application of the invention is a more complete extraction of platinum and precious metals.

table 2 Charge Experience number The composition of the charge, grams Extraction in silicon,% Cream-
niy Limestone Quartzite The waste is enriched -
niya Slag basicity NaCl Kcl Pt Rh Pd Au Ag one 380 8 120 400 0.2 one hundred one hundred 95 90 97 95 95 2 200 7 60 500 0.3 75 75 90 88 92 91 92 3 one hundred 59 180 500 0.35 fifty fifty 87 85 90 77 77 Proto-
type of four 70 70 77 56 60 Note: Slag basicity (CaO / SiO ₂ ) was calculated taking into account the CaO content in the enrichment waste 12% (by weight) and the SiO ₂ content - 37%.

Information sources

1. Graver N.S. The basics of metallurgy. v.5, M .: Metallurgy, 1968, p. 346-347.

2. Patent RU 2180011. IPC C22B 11/02, 7/00, 02.27.2002.

Claims (2)

1. The mixture for the extraction of precious metals in the metal phase during melting, consisting of raw materials containing precious metals, slag-forming on the basis of silica and limestone, fluxing and silicon as a solvent, characterized in that as fluxing it contains chlorides and fluorides of alkali and alkaline earth metals, and of these slag-forming - forming slag with a basicity of 0.2-0.35. 2. The method of extraction of precious metals into the metal phase during melting, including the preparation of a mixture from raw materials containing precious metals, slag-forming based on silica and limestone, fluxing and silicon as a solvent, melting and aging, cooling and separation of the metal phase from slag and flux, characterized in that the mixture is prepared using as mentioned slag-forming slag-forming slag with a basicity of 0.2-0.35, and as flux-forming - chlorides and fluorides of alkaline and alkaline earth Ferrous materials, melting, and exposure is carried out at a temperature 50-100 ° C above the melting temperature of the most refractory of the noble metal in the charge.