RU2360984C1 - Extraction method of platinum metals - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method includes mixture smelting, consisting of materials, consisting platinum group metals in iron-containing components, carbonaceous reductant and slag-forming materials, with concentration of extracted materials in ferric phase. Mixture smelting is implemented in previously heated up to the temperature 1600-1700°C arc-plasma furnace of direct current with cathode, installed at furnace bottom, at uniform introduction of mixture into the arc resistant area. After mixture introduction it is smelted and melt is isolated at the same temperature up to forming of castable melt and its concentration in the cathode area. Additionally amount of carbonaceous reductant is 5-30% of required calculated amount for full iron recovery.

EFFECT: increasing of extraction ratio of platinum group metals from materials, consisting these metals in crystal lattice of substances, or in structural carbonaceous clusters, or in other form, unavailable for its sterling analysis, extraction and concentration.

3 cl, 6 tbl, 2 ex

Description

The invention relates to the field of metallurgy, and in particular to methods for the extraction of platinum group metals, in particular, from hardly enriched materials, such as dumps of developed deposits.

All methods of beneficiation of mineral ores are based on the “disclosure” of the mineral phases and the redistribution of the useful mineral according to the given physical and chemical properties.

A known method for the extraction of platinum group metals, including melting the starting material based on non-base metal chalcogenides containing platinum group metals, in the presence of a carbon reducing agent and additives with the simultaneous use of sodium compounds and products containing iron-based metal alloys. Sodium carbonate, sodium sulfite or sodium thiosulfate were used as sodium compounds, followed by concentration of the extracted metals in the metallic, in particular iron, phase. The isolated product was crushed, processed as a concentrate of refining production (RU 2112064 С, С22В 11/02, May 27, 1998).

The disadvantage of this method is that the resulting product is a multicomponent heavy alloy, which requires a large consumption of acids to dissolve the platinum group metals from it, which are used to dissolve the base in subsequent refining production, as well as the need to use a large number of various equipment.

At present, evidence has been obtained of the wide distribution of platinum group metals (PGM), in particular platinum, in titanomagnetite ores and in carbon black schists, in which the occurrence of PGM is at the nano and micro levels and is due to their uniform dispersion. It is not possible to obtain an industrial PGM concentrate by mechanical action on the minerals of metasomatic ores. Chemical methods of hydrometallurgy to extract PGMs are not effective.

A method is known from the prior art, the technical result of which is an increase in the degree of extraction of noble metals due to an increase in eutectic melting of the degree of extraction of microdispersed phases (nanoparticles) and atoms of noble metals in dislocations (linear defects) and microcracks of the crystal lattices of the starting materials into the alloy. For this, the material from which the precious metals are extracted is mixed with an alkaline mixture and the mixture is eutectically melted to obtain an alloy of these metals. The mixture immediately before melting is subjected to mechanical activation for 0.0833-2 hours while maintaining the ratio of the input power of mechanical energy to the specific surface of the mixture in the range of 0.0133-25 W × kg × m ^-2 . Eutectic melting of the mixture is carried out at temperatures lying in the range above 500 ° C. The ratio of the mass of the charge to the weight of the material is selected in the range of 0.75-2, and the mixture used is a mixture of sodium tetraborate with sodium carbonate, sodium tetraborate with sodium bicarbonate, sodium tetraborate with sodium carbonate and lead monoxide, sodium tetraborate with sodium bicarbonate and lead monoxide (RU No. 2272084, IPC С22В 11/02, publ. 2006. 0320).

The reasons hindering the widespread use of the method are:

- the need to use lead monooxides in the process, which makes the process environmentally hazardous,

- a low percentage of PGM extraction from titanomagnetite ores when using this method.

A known method for the extraction of platinum group metals, adopted as a prototype, comprising melting the starting material in the presence of a carbon reducing agent, followed by concentration of the extracted metals in the iron phase. According to the invention, a charge containing at least 2 g / t of platinum group metals, silicate, iron and sulfide components is used as starting material, the carbon reducing agent is taken in excess to completely reduce the oxide components of iron and platinum group metals, melting is carried out until a heterogeneous sulfide melt is formed , silicate and iron phases, followed by separation of the iron phase concentrating the platinum group metals, and they are subjected to its oxidative treatment to completely isolate the meta lows of the platinum group (blast furnace and converter smelting) (RU 2224034, IPC С22В 11/02, publ. 2004.02.20).

The disadvantage of this method is the need for a complete reduction of iron oxides, as a result of the extraction product, a multicomponent alloy based on iron with a low content of platinum group metals in it is obtained. Therefore, to obtain a marketable product, enrichment of this alloy is required 50-100 times using oxidative smelting in an oxygen converter.

In addition, this method does not provide the extraction of platinum group metals found in ore materials and industrial waste in the form of complex microinclusions with carbon, sulfur and oxygen, the so-called clusters.

An object of the invention is the creation of conditions under which it is possible to extract platinum group metals from materials containing these metals in the crystal lattice of substances, or in structural carbon clusters, or in some other form, inaccessible for their full analysis, isolation and concentration.

The technical result from the use of the invention is to increase the degree of extraction of platinum group metals from natural materials using environmentally friendly methods.

This ensures an increase in the efficiency of use of natural resources, involvement in industrial processing with the aim of extracting platinum group metals from a number of new materials:

- metasomatites of various formation types attributable to off-balance ores and rocks,

- industrial products, ephels, sludges, ash and slag waste of TPPs operating on brown and coal.

The specified technical result is achieved due to the fact that in the method for the extraction of platinum group metals, including melting a mixture consisting of materials containing platinum group metals in iron-containing components, a carbon reducing agent and slag-forming materials, with a concentration of recoverable metals in the iron phase, the charge is melted in preheated to a temperature of 1600-1700 ° C of a direct current plasma-arc furnace with a cathode mounted on the bottom of the furnace, in the zone of a stable arc of which is equal to ERNO injected charge is melted, the melt is kept at the same temperature to form a flowable melt, and its concentration in the cathode zone, and the amount of the carbonaceous reducing agent is 5-30% of the calculated amount needed for complete reduction of iron. In this case, platinum-containing carbon materials are used as a carbon reducing agent, and platinum-resistant materials are used as materials containing platinum group metals in the iron-containing components.

Metallurgical processing is carried out in a special-design direct-current plasma-arc furnace.

A uniformly homogeneous mixture of crushed platinum-containing oxide materials, platinum-containing carbon reducing agents and fluxes is introduced into the zone of a stable electric arc of the furnace, the inner space of which is preheated to 1600-1700 ° C.

The electric power of the arc is selected so that it is sufficient to melt the injected mixture in the arc zone and to obtain liquid melts with a temperature of 1600-1700 ° C. At temperatures below 1600 ° C, the viscosity of the slag will be high enough, which will complicate the concentration of the Fe-Pt melt on the hearth of the furnace; temperatures above 1700 ° C may reduce the performance of the furnace lining or the need for highly refractory lining materials.

In the arc zone, stable microcomplexes containing platinum group metals and iron oxides are destroyed and ions of these metals and iron are formed. Under the influence of electrostatic and gravitational fields, ions of iron and metals of the platinum group are concentrated in the zone of the cathode installed in the hearth of the furnace.

The amount of carbonaceous reducing agent is 5-30% of the calculated amount necessary for the complete reduction of iron, which ensures partial reduction of iron and enrichment of the resulting melt. A reducing agent content of less than 5% will not provide the amount of reduced iron needed to dissolve the platinum; when the content is more than 30%, the refractoriness of the melt and the difficulty of draining it increase.

The use of a platinum-containing carbon reducing agent can further increase the percentage of extraction of platinum group metals.

The number and composition of fluxes is selected in such a way as to provide a low viscosity of a liquid melt of oxides (slag) at a temperature of 1600-1700 ° C.

Due to the unlimited solubility of platinum group metals in the liquid iron, a uniform melt of iron-metals of the platinum group is formed on the bottom of the furnace. To drain the alloy, the platinum group iron-metals use the lower drain hole, and to drain the slag - the upper drain hole.

The resulting metal concentrate contains more than 1% of the platinum group metals and PGM in its pure form is extracted from it at refineries by conventional chemical or electrochemical methods.

Examples of specific performance.

Example 1. As the initial mixture was taken:

1. 940 kg of enriched titanomagnetite with a content of iron oxides of 70%, other impurities consisting of oxides of Si, Ti, Al, etc., in an amount of 30% of the total mass. Based on the analysis results, the following PGM contents were determined, g / t.

Table 1. Analysis method Pt Pd Rh Microprobe neutron activation 1.88 Assay-atomic emission 0.04 0.08 > 0.02 Atomic absorption <0.02

2. 30 kg of coked coal underburning in the Pavlovsky section of the Primorsky Territory, obtained as a result of burning coal at the Vladivostok TPP-2, which is 30% of the minimum amount of carbon for the complete reduction of iron in titanomagnetite.

The results of analyzes of the content of platinum group metals in the underburning of coal are shown in table 2.

Table 2. Analysis method Pt, g / t Pd g / t Rh g / t Atomic absorption 1,6 0.2 0.2 Assay smelting, atomic absorption 3.0 0.3 0.3

3. 300 kg of quicklime produced by JSC Zhiguli.

4. 30 kg of foamed vermiculite of the Koksharovskoye field.

All components of the mixture were mixed to a homogeneous mixture and loaded into the hopper of the feeder, a total of 1300 kg. The plasma-arc furnace was preheated to a temperature of 1700 ° C on an electrically conductive charge. When the furnace was operating in the voltage mode - 100 V, the current strength - 7000 A, 1300 kg of charge were introduced uniformly over the course of 3 hours using the feeder into the arc zone. After the introduction of the charge, the melt in the furnace was aged for 20 minutes. Then, through the upper drain hole, liquid slag was drained, about 1240 kg, and through the lower drain hole 47 kg of molten iron-platinum group metals.

According to the analysis, the obtained metal concentrate has the following PGM contents, g / t: in the alloy / in terms of the initial one.

Table 3. Analysis method Pt Pd Rh LA-ICP / MS 11280 / 40.8 1545 / 5.25 712 / 2.42 ICP / MS 11681 / 42.25 2671 / 9.08 979 / 3.33

In terms of the total PGM content in the raw materials of the charge, the obtained PGM content exceeds the input analysis by 20 times, therefore, it is impossible to calculate the percentage of PGM extraction using the applied method due to the imperfection of laboratory methods for analyzing PGM for carbon man-made materials and iron ores.

Example 2. As the initial mixture was taken:

1. Reducer: 40 kg of shale, the amount of carbon - 50% (20 kg), 5%. from the required calculated amount for the complete reduction of iron. The results of analyzes for the content of PGM (g / t) are shown in Table 1.

Table 1. Analysis method Pt Pd Rh Atomic absorption 0.5 0.2 0.2 Assay smelting, atomic absorption 2.0 0.4 0.4

2. 800 kg of titanomagnetite, iron oxides 75% and impurities consisting of oxides of Si, Ti, Al, etc., in the sum of components> 20% of the total mass. Based on the results of the analyzes, the following PGM contents (g / t) were established:

Table 2. Analysis method Pt Pd Rh Microprobe neutron activation 1.88 Assay-atomic emission 0.04 0.08 > 0.02 Atomic absorption <0.02

3. 200 kg of quicklime granular lime production of JSC "Lada".

4. 40 kg of foamed vermiculite from the Koksharovskoye field.

All components of the charge were mixed to a homogeneous mixture and loaded into the hopper of the feeder, a total of 1080 kg of charge. The plasma-arc furnace was preheated to a temperature of 1600 ° C on an electrically conductive charge.

When the furnace was operating in automatic mode (U = 100V; I = 7000A), the entire charge was introduced into the arc zone with the help of a feeder uniformly for 2.5 hours. After the introduction of the charge, the melt in the furnace was aged for 20 minutes.

Then, through the upper drain hole, liquid slag was drained of about 1000 kg, and through the lower drain hole - 41 kg of molten iron-platinum group metals.

According to the analysis, the obtained metal concentrate has the following PGM contents, g / t: in the alloy / in terms of the starting material.

Table 3. Analysis method Pt Pd Rh LA-ICP / MS 10448 / 51.0 1065 / 5.2 1220 / 5.9 ISP / MS 10600 / 51.2 1080 / 5.3 1320 / 6.3

In terms of the total PGM content in the raw materials of the charge, the obtained PGM content exceeds the input analysis by 25 times, therefore, it is impossible to calculate the percentage of PGM extraction using the applied method due to the imperfection of laboratory methods of PGM analysis for carbon man-made materials and iron ores.

From the above examples it follows that the obtained PGM content exceeds the input analysis by 20-25 times. The actual PGM recovery is 40-45 g per 1 ton of ore processed.

Claims (3)

1. The method of extraction of platinum group metals from materials containing platinum group metals in iron-containing components, comprising melting a mixture consisting of materials containing platinum group metals in iron-containing components, a carbon reducing agent and slag-forming materials, with a concentration of recoverable metals in the iron phase, characterized in that the mixture is melted in a preheated to a temperature of 1600-1700 ° C plasma arc direct current furnace with a cathode mounted on a hearth oven for uniform introduction of the charge into the stable arc zone, it is melted and the melt is kept at the same temperature to form a flowable melt, and its concentration in the cathode zone, and the amount of the carbonaceous reducing agent is 5-30% of the calculated amount needed for complete reduction of iron. 2. The method according to claim 1, characterized in that platinum-containing carbon materials are used as the carbon reducing agent. 3. The method according to claim 2, characterized in that as materials containing platinum group metals in the iron-containing components, refractory platinum-containing materials are used.