Method of processing nitration hydroxides in refinery of platinum metals

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy of noble metals, in particular, to method of processing nitration hydroxides in refinery of platinum metals containing chalcogenides, tin, arsenium and platinum group metals, gold and silver. Proposed method comprises leaching of hydroxides and extracting basic metal compounds from the solution. Hydroxide leaching is carried out for 1-2 h by alkali solution with concentration of 140-180 g/l with l:S ratio varying from 3:1 to 4:1, temperature 80-90°C, and introducing hydrazine hydrate into pulp to reach OVP of minus 400-600 mV relative to reference silver-chloride electrode. Then, alkaline solution is separated from insoluble residue that concentrates platinum metals. Now, extraction of basic metals is carried out in processing alkaline solution by sulfuric acid to pH=4-5 to produce hydroxide precipitate of tin, arsenium, selenium and tellurium, and by filtration, or processing of alkaline solution by sulfuric acid to pH 0.5-1.0 along with adding iron powder to OVP varying from 0 to minus 100 mV, and filtration of obtained cementates obtained on the basis of selenium and tellurium, and processing the solution by alkali to pH = 4-5 with deposition of tin and arsenium hydroxides. Invention allows extracting up to 85% of Se and Te into target products, 90% of Sn and As into secondary hydroxides at minimum transition (less than 1%) into PMH.

EFFECT: over 99% of platinum metals left in refinery cycle, reduced processing cycle.

4 tbl

 

The invention relates to the field of metallurgy of non-ferrous metals, particularly to the refining of platinum group metals.

Hydroxide precipitation (hydroxides) nitration formed on the processing of chloride solutions of platinum group metals (PGM) solution of sodium nitrite. During this IPY into solution - oriented product for refining and impurity nonferrous metals form a precipitate of simple and complex hydroxide compounds, gold seacadets in the elemental form. Part of the IPY strongly sorbed on the sediment hydroxides or is in the metallic form and cannot be removed by washing. The PGM content in the sediment conditioned hydroxides nitration is 0.2 to 1.0%, gold up to 0.2%. The basis hydroxides are complex compounds of copper, iron, selenium, tin, tellurium, arsenic and lead.

Involvement hydroxides directly in the cycle refining production leads to almost complete loop of impurity elements in refineries production due to the lack of channels output from the process cycle. As a consequence, the necessary processing in a separate process chain.

A method of refining hydroxides nitration, comprising: dissolving them in a weak hydrochloric acid, the processing solution of sodium nitrite, filtering the slurry and washing the precipitate obtained hydrox the Dov base metals with water or a weak solution of NaCl. (Analytical chemistry of platinum metals. M. Nauka, 1972, s; Manual on chemical analysis of platinum metals and gold. Ginsburg, S. and others, M. Nauka, 1965 s.255; Fumes Analytical chemistry of the noble metals. part 1., M. Mir, 1969, p.131.) The most detailed method set out in the source.

This method is adopted as a prototype. The main disadvantages of the prototype are:

- high consumption of hydrochloric acid (about 2 kg/kg hydroxides) for the complete dissolution of the precipitate hydroxides and sodium nitrite (about 1.5 kg/kg hydroxides) to re-precipitated base metals;

the low concentration of platinum metals in solution (1-2 g/l);

- the impossibility of dissolving in hydrochloric acid metallic gold and PGM, which are partly in the metal hydroxides in the form that does not allow for the complete separation of PGMs and gold from base metals;

- the impossibility of selective separation of base metals, which does not allow to realize the residue of their hydroxides.

The technical result, which directed the present invention is the determination of the optimum parameters of the separation of PGMs and impurity elements (Se, Te, Sn, As) at the stage alkaline leaching hydroxides and subsequent selective extraction from alkaline solution by Poluchenie derived from refining production selective Se-Te and Sn-As concentrates. PGM almost entirely remains in the insoluble residue alkaline leaching.

Implementation of the technical result is achieved by the known method of processing hydroxides nitration refining production of platinum metals containing platinum metals, selenium, tellurium, tin, arsenic, including the leaching of hydroxides and subsequent extraction from a solution of the compounds of base metals, alkali hydroxides spend 1-2 hours with alkali solution with a concentration of 140-180 g/l with respect to W:t from 3:1 to 4:1, a temperature of 80-90°C, with the introduction of the slurry of hydrazine hydrate to achieve AFP minus 400-600 mV relative to silver chloride reference electrode, with the separation of the alkaline solution from the insoluble residue concentrating platinum metals, subsequent extraction of base metals are the alkaline processing solution with sulfuric acid to pH 4-5 with getting hydroxide precipitate tin, arsenic, selenium and tellurium and its filtering or processing of the alkaline solution of hydrochloric acid to achieve a pH of 0.5-1.0 with the introduction of iron powder to achieve the AFP from 0 to -100 mV, filtering the received cementation selenium and tellurium, and treatment solution of alkali to pH 4-5 with precipitation of the hydroxides of tin and arsenic.

The method consists in ensuring the icenii selective dissolution in an alkaline environment, Se, Te, Sn, As, under controlled parameters of temperature, NaOH concentration, the ratio of W:t, the value of redox potential (ORP) while preventing the transition into the solution IPY. From the alkaline solution may almost full (96-98%) isolation of Se, Te, Sn, As in the hydroxide precipitate, containing not more than 50 g/t Σ processing solution with sulfuric acid to achieve a pH of 4-5. However, it is more efficient group division Se and Te from Sn and As. Selective removal of Se and Te of the alkaline solution is provided by sequential treatment with hydrochloric acid and iron powder with optimal control of pH and ORP. Then from the acidic solution by treatment with alkali extract in the form of hydroxides of tin and arsenic in achieving optimal pH value.

Parameter optimization processing hydroxides nitration containing platinum metals, selenium, tellurium, tin, arsenic, is the maximum degree of extraction in alkaline solution during leaching of impurity elements and the minimum transition in a solution of platinum metals. During subsequent processing of the alkaline solution are optimal maximum selective extraction from the solution of Se and Te in the concentrate with minimal transition in his Sn and As. Then from the solution fully remove Sn and As.

The decrease in the concentration of alkali m is it 140 g/l, relations t:W less than 3:1, temperature less than 80°C, duration of leaching less than 1 hour and ORP values exceed minus 400 mV does not ensure the completeness of extraction of Se, Te, Sn, As and minimum extraction of platinum group metals in solution.

Increasing the alkali concentration of more than 160 g/l relations W:t more than 4:1 positive effect on removing impurity elements in the solution does not, but leads to additional unproductive consumption of alkali.

The increased duration of the leaching more than 2 hours does not give a positive effect of increasing the extraction of Se, Te, Sn, As in solution, but leads to performance degradation. The increase in temperature over 90°C causes a danger of discharge of slurry from the reactor due to the boiling solution and intense reaction. Reducing the value of the redox potential of the solution is less than minus 600 mV leads to the restoration of Te to the elemental state and reduce its extraction into the solution.

At the stage of selective extraction of Se and Those of the alkaline solution, the pH value is more than 1 when the alkaline processing solution in the acid does not provide selectivity group Department of Se and Te from Sn and As. The ORP value of more than 0 in the processing phase, the acid solution of iron powder does not provide maximum efficiency of extraction of platinum group metals in the sediment Se-Te and PGM permanently lost with Sn-As sludge. The value of the redox potential of less than minus 100 mV and a pH of less than 0.5 when the result in unproductive waste of iron powder, allocation of explosive hydrogen and toxic arsina cars (AsH3).

Being processed with alkali acid solution after separation of tellurium and selenium optimal is to achieve a pH of 4-5, which ensures maximum weight selection Sn-As precipitates of hydroxides. At pH values>5 positive effect is not achieved, and at pH values<4 removing the Sn and As in sediment decreases.

As the object was used for the standard sample of the hydroxides nitration (after pre-selective extraction of PGMs and copper), a composition close to the average monthly samples. The composition of the hydroxides (%)

PtPdRhIrENΣAu, AgPbCuFeNiTeSeSnAs
0,010,0230,0350,0080,0520,0228,02,0 22,00,2to 12.010,016,04,3

Examples of the method on the proposed regulations are presented in tables 1-4.

55 4:1
Table 1
The dependence of extraction in alkaline solution, Se, Te, Sn, As, from the controlled parameters
№ p/pConditions leachExtraction into solution, %
The concentration of alkali, g/lThe ratio of W:tDuration, hoursTemperature,
°C
ORP, mVΣSeTheSnAs
11004:1190-5001,7754571
21404:1190-4801,987777785
31804:1190-4851,993848991
42004:1190-4751,894848992
51603:1190-4901,792818889
61602:1190-4901,879617283
71605:1190-4751,994849092
81604:10,590-4501,972706973
91604:1290-4951,895859093
10 1604:1190-4701,995858993
111604:1180-4852,192808890
121604:1170-4852,782698089
131604:1190-5152,092769092
14160190-3502,593519091
151604:1190-6001,690859192
161604:1190-8001,286309091
171604:1190-1004,892209092

The optimal parameters for alkaline leaching hydroxide: NaOH concentration 140-180 g/l, the ratio of W:t from 31 to 4:1, temperature (80-90°C, duration 1-2 hours, the introduction of hydrazine hydrate to the value of the redox potential minus (400-600) mV, provide extract in a solution of 85 to 90% of selenium, 75-85% of tellurium, 75-90% tin and 85-90% of arsenic with minimal (less than 2%) transition in the PGM solution.

Hydrazine hydrate is administered for the purpose of translation insoluble compounds tellurium (+6) in a well-soluble compounds (+4), and to restore to metals partially converted to the alkaline solution of the IPY.

Reducing the alkali concentration of less than 140 g/l (experiment 1), relations W:t to 2:1 (6), the duration of the leaching less than 1 hour (experiment 8) and temperatures below 80°C (experiment 12) leads to a decrease in the extraction of Se, Te, Sn, As in the solution of 10-30% by reducing the chemical activity of the environment leaching.

Increasing the alkali concentration of more than 160 g/l (experiment 4), relations W:t more than 4:1 (experiment 7) and duration of leaching more than 2 hours (experiment 10), the positive effect is not given, but lead to an unproductive waste alkali and performance.

The value of the redox potential of the pulp more minus 400 mV (experience 14,17) and less than minus 600 mV (experiment 16) lead to a decrease in the extraction of tellurium in the solution. With a more positive redox potential this is due to the incompleteness of the transition insoluble forms of The+6in soluble Ones+4and with a more negative redox potential Those+4goes partially what about the element in The 0also insoluble.

When collective precipitation from alkaline solution, Se, Te, Sn, As is optimal processing solution of sulfuric acid to achieve a pH of 4-5 (table 2, experiment 2).

Table 2
The dependence of the extraction elements in the hydroxide precipitate (%)
№ p/pPHThe degree of extraction of elements in the hydroxide precipitate (%)
TeSeSnAs
16,091,285,482,166,2
24,597,498,097,396,2
33,089,691,288,776,2

At higher pH values (experiment 1) removing ELEH the clients in the sludge is reduced by 7-15% (Se, Te, Sn) and 30% (As).

By reducing the pH to 3 the resulting precipitate begins to dissolve in an acidic environment and removing elements in the sediment also decreases by 8-20% (experiment 3).

Content Σ in collective hydroxide precipitation is not more than 50 g/so

The maximum recovery of PGM, Se, Te precipitates is provided when handling alkaline solution of hydrochloric acid to a pH of 0.5-1 (experiments 2,3,5-8 in table 3) and subsequent treatment of the solution with the iron powder to the value of the redox potential from 0 to minus 100. More positive ORP value (experiment 5) reduces the extraction of platinum group metals in the sediment, which is undesirable, since the subsequent operations they will be lost with Sn As a product. More negative than -100 mV, ORP value (experiment 8) and the pH value is less than 0.5 (experiment 1) lead to an unproductive waste of iron powder, the allocation of explosive hydrogen and toxic AsH3(arsina cars). The pH value is more than 1 (experiment 4) leads to poor dissolution of the formed hydroxides in the alkaline processing solution acid, pollution, sediment Se, Te, tin, arsenic and iron, incomplete extraction of PGMs and tellurium.

Table 3
The dependence of extraction of selenium and tellurium in cemented from process parameters
№ p/pConditions dissolve the precipitate hydroxides and restorative treatment solutionRemoving elements from solution in cemented, %
PHThe value of the redox potential, mVThe consumption of Fe, g/lΣSeTeSnAs
10-95369999,899,74,075,0
20,5-80279999,899,56,055,0
31-75259999,899,56,050,0
4**1,5-85279599,892,02,047,0
50,5105207599,598,0048,0
60,50239599,899,32,053,0
70,5-100299999,899,59,059,0
80,5-150359999,899,616,071,0
** incomplete dissolution of the hydroxide

The maximum recovery of the hydrochloric acid solution of Sn and As when the alkali treatment is provided when the value of pH 4-5 (table 4). With a larger value of the positive effect of no, while values smaller than 4, the recovery in the sludge is reduced by 10-20%.

Table 4
Awesomest extraction of tin and arsenic precipitates of hydroxides from pH
№ p/pPHRemoving the hydroxides, %
SnAs
138576
249495
359796
469696

A method of processing hydroxides nitration refining production of platinum metals, with whom containing a series of platinum metals, selenium, tellurium, tin, arsenic, including the leaching of hydroxides and subsequent extraction from a solution of the compounds of base metals, characterized in that the alkali hydroxides spend 1-2 hours with alkali solution with a concentration of 140-180 g/l with respect to W:t from 3:1 to 4:1, a temperature of 80-90°C, with the introduction of the slurry of hydrate of hydrazine to achieve AFP minus 400-600 mV relative to silver chloride reference electrode, with the separation of the alkaline solution from the insoluble residue, concentrating platinum metals, subsequent extraction of base metals are the alkaline processing solution with sulfuric acid to pH 4-5 obtaining hydroxide precipitate tin, arsenic, selenium and tellurium and its filtering or processing of the alkaline solution of hydrochloric acid to achieve a pH of 0.5-1.0 with the introduction of iron powder to achieve the AFP from 0 to -100 mV, filtering the received cementation selenium and tellurium, and treatment solution of alkali to pH 4-5 with precipitation of the hydroxides of tin and arsenic.



 

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2 ex

FIELD: metallurgy.

SUBSTANCE: procedure consists in concentrating refractory ore with successive concentrate fine crumbling to release gold with extracting solution and in mixing fine crumbled concentrate with wastes or by-products of concentrating to facilitate filtering said concentrate mixed with said wastes of concentrating. Here is also disclosed the installation for implementation of the said procedure.

EFFECT: increased rate of processing of refractory mineral ore avoiding harmful effect to environment.

14 cl, 4 dwg, 1 ex

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