A method for dissolving iron in a high-silicon high-tungsten iron alloy enriched with noble metals

Abstract

The present application relates to a kind of iron-rich dissolving method of high-silicon high-tungsten iron alloy, belongs to the technical field of precious metal enrichment smelting.The present application is with iron trichloride as oxidant, and the first stage of oxidation dissolution is carried out in dilute hydrochloric acid solution to the high-silicon high-tungsten iron alloy of precious metal enrichment, and most of iron, copper, nickel etc. enter solution;With sodium hydroxide solution as leaching agent, the second stage of mechanical activation dissolution is carried out to the insoluble residue after the first stage of dissolution, and most of tungsten, silicon, chromium etc. enter solution;With iron trichloride as oxidant, the third stage of oxidation dissolution is carried out in dilute hydrochloric acid solution to make residual acid-soluble base metal such as iron enter solution.After three stages of dissolution, the large amount of base metal including iron in the high-silicon high-tungsten iron alloy of precious metal enrichment is dissolved in solution, and total weight loss rate of solid is about 80~85%, so that platinum, palladium, rhodium, iridium, ruthenium etc. are effectively enriched, and iron trichloride is reduced to generate ferrous chloride in the process of oxidation dissolution, which can be regenerated to iron trichloride by oxidizing agent.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of iron dissolution method of enriching noble metal high-silicon high-tungsten iron alloy, belong to noble metal enrichment smelting technical field. BACKGROUND

[0002] At present, the iron dissolution method of enriching noble metal high-silicon high-tungsten iron alloy, traditional process is to add acid to dissolve iron at a certain temperature or to add oxidizing agent under acidic conditions to dissolve iron. However, due to the inclusion of silicon, tungsten and other metals, the iron dissolution rate is greatly reduced if only acid is used for dissolution, sometimes the highest can only dissolve 15-20% of the total amount of iron. If a strong oxidizing agent such as hydrogen peroxide is added under acidic conditions to dissolve iron, the noble metal will be dissolved and dispersed in the iron dissolution solution at the same time, which will greatly reduce the direct recovery rate of noble metal, seriously affect the next stage of noble metal dissolution and purification process, and reduce the production efficiency. SUMMARY

[0003] In view of the dissolution difficulty and noble metal dissolution dispersion in the current iron dissolution of noble metal high-silicon high-tungsten iron alloy, the present application proposes an iron dissolution method of enriching noble metal high-silicon high-tungsten iron alloy, which can effectively increase the enrichment content of noble metal and reduce the dissolution dispersion of noble metal in the iron dissolution solution. With weakly oxidizing ferric chloride as oxidizing agent, the noble metal high-silicon high-tungsten iron alloy is subjected to first-stage oxidative dissolution in dilute hydrochloric acid solution, most of the acid-soluble metals such as iron, copper and nickel enter the solution, and the solid weight reduction rate is about 60%; sodium hydroxide solution is used as leaching agent to perform second-stage mechanical activation dissolution on the insoluble residue after the first-stage dissolution, most of the tungsten, silicon and chromium enter the solution, and the solid weight reduction rate is about 10-15%; ferric chloride is used as oxidizing agent to perform third-stage oxidative dissolution in dilute hydrochloric acid solution, so that the residual acid-soluble base metals such as iron enter the solution, and the solid weight reduction rate is about 10-15%. After three-stage dissolution, a large amount of base metals including iron in the noble metal high-silicon high-tungsten iron alloy are dissolved in the solution, and the total solid weight reduction rate is about 80-85%, so that the noble metals such as platinum, palladium, rhodium, iridium and ruthenium are effectively enriched (from about 3-5% before enrichment to about 25-30%), and the ferric chloride is reduced to ferrous chloride during oxidative dissolution, which can be oxidized by oxidizing agent to regenerate ferric chloride for reuse.

[0004] An iron dissolution method of enriching noble metal high-silicon high-tungsten iron alloy, the specific steps are as follows:

[0005] (1) crushing the high-silicon high-tungsten iron alloy enriched in noble metals to obtain high-silicon high-tungsten iron alloy powder, under stirring, adding the high-silicon high-tungsten iron alloy powder into dilute hydrochloric acid, reacting at a temperature of 80-90℃ for 20-40min, then adding excess solid ferric chloride to perform a first-stage oxidative dissolution reaction, cooling to room temperature, and performing solid-liquid separation to obtain insoluble residue A1 and filtrate B1, and the insoluble residue A1 is washed to neutral with water;

[0006] (2) adding the insoluble residue A1 into a mechanical activation mill, adding sodium hydroxide solution, performing a second-stage activation ball milling leaching for 60-120min, then adding an equal volume of water for dilution, and performing solid-liquid separation to obtain filter residue A2 and filtrate B2, and the insoluble residue A2 is washed to neutral with water;

[0007] (3) adding the insoluble residue A2 into a stirring reaction kettle, under stirring at a temperature of 80-90℃, adding dilute hydrochloric acid and excess solid ferric chloride to perform a third-stage oxidative dissolution reaction for 3-4h, cooling to room temperature, and performing solid-liquid separation to obtain insoluble residue A3 and filtrate B3, and the insoluble residue A3 is washed to neutral with water, and dried to obtain a noble metal enriched residue.

[0008] In mass percentage, the high-silicon high-tungsten iron alloy enriched in noble metals in step (1) has the following composition: iron content not less than 65%, silicon content 8-13%, tungsten content 3-10%, chromium content 2-5%, copper content 1-4%, nickel content 0.5-2%, iridium content <0.5%, platinum content 1-2%, palladium content 1-2%, rhodium content 0.5-2%, and gold and silver content both <1%.

[0009] Preferably, in the high-silicon high-tungsten iron alloy powder in step (1), the mass percentage of powder with particle size less than 80 mesh is not less than 85%.

[0010] Preferably, in step (1), the concentration of dilute hydrochloric acid is 1.5-3.0mol / L, and the solid-liquid ratio g:mL of high-silicon high-tungsten iron alloy powder to dilute hydrochloric acid is 1:3-5.

[0011] Preferably, in step (1), the addition amount of solid ferric chloride is 1.2-1.5 times of the theoretical amount, the oxidative dissolution reaction temperature is 80-90℃, and the time is 3-5h.

[0012] Preferably, in step (2), the concentration of sodium hydroxide solution is 4-6mol / L, the solid-liquid ratio g:mL of insoluble residue A1 to sodium hydroxide solution is 1:3-5, the activation ball milling leaching speed is 50-100r / min, and the activation ball milling leaching temperature is 80-90℃.

[0013] Preferably, in step (3), the concentration of dilute hydrochloric acid is 1.5-3mol / L, and the solid-liquid ratio g:mL of insoluble residue A2 to dilute hydrochloric acid is 1:3-5.

[0014] Preferably, the amount of the ferric trichloride solid added in the step (3) is 1.2-1.5 times of the theoretical amount.

[0015] The high-silicon high-tungsten high-noble metal iron alloy mainly contains platinum, rhodium, palladium, iridium, ruthenium, gold, silver, tin, iron, sodium, potassium, silicon, tungsten, copper, nickel and the like. Except for platinum group metals, the proportion of acid-insoluble matters such as silicon and tungsten is relatively high, which will seriously hinder the further dissolution of iron. The present application adopts the way of step-by-step dissolution, which not only effectively solves the problems of tungsten and silicon wrapping, but also effectively reduces the dissolution and dispersion of noble metals, greatly improves the dissolution rate of iron and the noble metal enrichment content in the noble metal-rich iron alloy. That is, the trivalent iron salt with relatively weak oxidizing property is used to replace the strong oxidizing agents such as hydrogen peroxide and sodium chlorate, which can greatly reduce the dispersion of noble metals in the iron dissolution solution during iron dissolution; the method of mechanical activation and secondary alkali leaching is used to remove silicon and tungsten, which can effectively reduce the wrapping of silicon in the form of silicon dioxide and tungsten in the form of tungstic acid on iron during acid dissolution of iron, and effectively improve the dissolution rate of iron. The main reactions are as follows:

[0016] First-stage dissolution:

[0017] Fe + 2HCl → FeCl2+ H2↑ (1)

[0018] 2Fe 3+ + Fe → 3Fe 2+ (2)

[0019] Second-stage dissolution:

[0020] WO3+2NaOH→ Na2WO4 + H2O (3)

[0021] SiO2+ 2NaOH → Na2SiO3+H2O (4)

[0022] Third-stage dissolution:

[0023] Fe + 2HCl → FeCl2+ H2↑ (5)

[0024] 2Fe 3+ + Fe → 3Fe 2+ (6)

[0025] After three-stage dissolution, a large amount of base metals including iron in the high-silicon high-tungsten high-noble metal iron alloy are dissolved in the solution, so that the noble metals such as platinum, palladium, rhodium, iridium and ruthenium are effectively enriched.

[0026] The beneficial effects of the present application are:

[0027] (1) The present application adopts a "three-stage dissolution method" to dissolve the acid and alkali soluble metals including iron, tungsten and silicon in high-silicon and high-tungsten alloys, namely, "one-stage iron dissolution by ferric chloride-two-stage mechanical activation alkali dissolution of silicon and tungsten-three-stage iron dissolution by ferric chloride". The three-stage iron dissolution method can effectively improve the iron dissolution rate, thereby greatly increasing the enrichment content of noble metals, effectively reducing the dispersion of noble metals in the iron dissolution solution, and the acid and alkali soluble metal dissolution rate of iron, tungsten and silicon reaches 80-85%, and the noble metal enrichment content reaches 25-30%;

[0028] (2) The ferric chloride dissolves iron into ferrous chloride, which is oxidized into ferric chloride by an oxidizing agent such as air, and can be reused as an oxidizing agent. Compared with the existing process, the consumption of reagents can be greatly reduced. For example, the unit consumption of hydrogen peroxide during iron dissolution can be reduced to 0.68 g H2O2 / g Fe.

[0029] (3) The present application uses weakly oxidizing ferric chloride to replace strongly oxidizing hydrogen peroxide, chlorate and chlorine gas to dissolve iron, which can reduce the content of noble metals in the iron dissolution solution and improve the direct recovery rate of noble metals. The direct recovery rate of noble metals in the enrichment slag is >99.25%, and the total content of noble metals in the iron dissolution solution can be reduced from >0.1 g / L by the traditional iron dissolution method to <0.1 g / L. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below in conjunction with specific embodiments, but the scope of protection of the present application is not limited to the content described.

[0031] Example 1: The high-silicon and high-tungsten noble metal enriched iron alloy in this embodiment is obtained by fire reduction smelting enrichment of waste catalyst, and the main elements in the alloy are platinum, palladium, rhodium, ruthenium, iridium, gold, silver, tin, iron, sodium, potassium, silicon, tungsten, copper, nickel, etc. The main specific component contents are shown in Table 1 below:

[0032] Table 1 Main component contents of high-silicon and high-tungsten noble metal enriched platinum alloy (%)

[0033] ;

[0034] A method for dissolving iron in a high-silicon and high-tungsten iron alloy enriched with noble metals, the specific steps are as follows:

[0035] (1) 100g high-silicon high-tungsten iron alloy enriched in precious metals is crushed to obtain high-silicon high-tungsten iron alloy powder (the mass fraction of powder with a particle size of less than 80 mesh is not less than 86%), and the high-silicon high-tungsten iron alloy powder is added to dilute hydrochloric acid with a concentration of 2 mol / L (the solid-liquid ratio g:mL of high-silicon high-tungsten iron alloy powder to dilute hydrochloric acid is 1:5) under stirring, and reacted at a temperature of 80°C for 35 min, then excess ferric chloride solid (1.5 times the theoretical amount) is added and a first-stage oxidative dissolution reaction is carried out at a temperature of 80°C for 3h, and cooled to room temperature, and solid-liquid separation is performed to obtain 41.14g insoluble residue A1 and filtrate B1, and the insoluble residue A1 is washed to neutral with water; the weight loss of this dissolution stage is 58.86%, the total content of precious metals is 11.67%, and the direct recovery rate of precious metals is 99.79%;

[0036] (2) The insoluble residue A1 is added to a mechanical activation mill, and a sodium hydroxide solution with a concentration of 5 mol / L is added (the solid-liquid ratio g:mL of insoluble residue A1 to sodium hydroxide solution is 1:5), and a second-stage activation leaching is carried out at a ball milling speed of 80 r / min and a temperature of 80°C for 110 min, then an equal volume of water is added for dilution, and solid-liquid separation is performed to obtain 28.78g filter residue A2 and filtrate B2, and the insoluble residue A2 is washed to neutral with water; the weight loss of this dissolution stage is 12.36%, the total content of precious metals is 16.65%, and the direct recovery rate of precious metals is 99.83%;

[0037] (3) The insoluble residue A2 is added to a stirring reaction kettle, and a dilute hydrochloric acid with a concentration of 2 mol / L (the solid-liquid ratio g:mL of insoluble residue A2 to dilute hydrochloric acid is 1:5) and excess ferric chloride solid (1.5 times the theoretical amount) are added under stirring at a temperature of 85°C for a third-stage oxidative dissolution reaction for 3h, and cooled to room temperature, and solid-liquid separation is performed to obtain insoluble residue A3 and filtrate B3, and the insoluble residue A3 is washed to neutral with water, and dried to obtain 17.30g precious metal enrichment residue; the weight loss of the iron alloy in this dissolution stage is 12.36%, the content of precious metals is 27.69%, and the recovery rate of precious metals is 99.92%;

[0038] The precious metal content of the precious metal enrichment residue obtained after three-stage iron dissolution in this example is analyzed and shown in Table 2; the precious metal content in the iron dissolution liquid is shown in Table 3;

[0039] Table 2 Precious metal content in iron dissolution residue

[0040] ;

[0041] Table 3 Precious metal content in iron dissolution liquid

[0042] ;

[0043] After three-stage dissolution in this example, the total direct recovery rate of precious metals including platinum, palladium, rhodium, iridium, ruthenium, gold, and silver reaches 99.54%.

[0044] Example 2: The high-silicon high-tungsten precious metal-enriched ferroalloy in this embodiment is obtained by fire reduction smelting of waste catalyst, and the main elements in the alloy are ruthenium, gold, silver, tin, iron, sodium, potassium, silicon, tungsten, copper, nickel, etc., and the main specific component contents are shown in Table 4 below:

[0045] Table 4 Main component contents of high-silicon high-tungsten precious metal-enriched platinum alloy (%)

[0046] ;

[0047] A method for dissolving iron in a high-silicon high-tungsten iron alloy enriched with precious metals, the specific steps are as follows:

[0048] (1) 100 g of high-silicon high-tungsten iron alloy enriched with precious metals is crushed to obtain high-silicon high-tungsten iron alloy powder (the mass fraction of powder with a particle size of less than 80 mesh is not less than 87.5%), under stirring conditions, the high-silicon high-tungsten iron alloy powder is added to dilute hydrochloric acid with a concentration of 3 mol / L (the solid-liquid ratio g:mL of high-silicon high-tungsten iron alloy powder to dilute hydrochloric acid is 1:4), and the reaction is carried out at a temperature of 90°C for 25 min, then excess ferric chloride solid (1.3 times the theoretical amount) is added and a first-stage oxidation dissolution reaction is carried out at a temperature of 90°C for 4 h, and then cooled to room temperature, and solid-liquid separation is carried out to obtain 44.23 g of insoluble residue A1 and filtrate B1, and the insoluble residue A1 is washed to neutral with water; the weight loss in this dissolution stage is 55.77%, the total content of precious metals is 13.11%, and the direct recovery rate of precious metals is 99.82%;

[0049] (2) The insoluble residue A1 is added to a mechanical activation mill, a sodium hydroxide solution with a concentration of 6 mol / L is added (the solid-liquid ratio g:mL of insoluble residue A1 to sodium hydroxide solution is 1:4), a second-stage activation leaching is carried out at a ball milling speed of 90 r / min and a temperature of 85°C for 90 min, then an equal volume of water is added for dilution, and solid-liquid separation is carried out to obtain 30.91 g of filter residue A2 and filtrate B2, and the insoluble residue A2 is washed to neutral with water; the weight loss in this dissolution stage is 13.32%, the total content of precious metals is 18.74%, and the direct recovery rate of precious metals is 99.86%;

[0050] (3) The insoluble residue A2 is added to a stirring reaction kettle, a dilute hydrochloric acid with a concentration of 3 mol / L (the solid-liquid ratio g:mL of insoluble residue A2 to dilute hydrochloric acid is 1:4) and excess ferric chloride solid (1.3 times the theoretical amount) are added under stirring at a temperature of 85°C for a third-stage oxidation dissolution reaction for 4 h, and then cooled to room temperature, and solid-liquid separation is carried out to obtain insoluble residue A3 and filtrate B3, and the insoluble residue A3 is washed to neutral with water, and then dried to obtain 20.14 g of precious metal-enriched residue; the weight loss of the ferroalloy in this dissolution stage is 10.77%, the content of precious metals is 28.67%, and the recovery rate of precious metals is 99.69%;

[0051] The precious metal content of the precious metal enriched slag obtained after three-stage iron dissolution in this embodiment is shown in Table 5; the precious metal content in the iron dissolution liquid is shown in Table 6.

[0052] Table 5 Precious metal content of iron dissolution slag

[0053] ;

[0054] Table 6 Precious metal content in iron dissolution liquid

[0055] ;

[0056] After three-stage dissolution in this embodiment, the total recovery rate of precious metals including platinum, palladium, rhodium, iridium, ruthenium, gold and silver is 99.37%.

[0057] Example 3: The high-silicon high-tungsten precious metal enriched iron alloy in this embodiment is obtained by fire reduction smelting enrichment of waste catalysts, and the main elements in the alloy are ruthenium, gold, silver, tin, iron, sodium, potassium, silicon, tungsten, copper, nickel, etc., and the main specific component contents are shown in the following Table 7:

[0058] Table 7 Main component content (%) of high-silicon high-tungsten precious metal platinum alloy

[0059] ;

[0060] A method for dissolving iron in a high-silicon high-tungsten iron alloy enriched with precious metals, the specific steps are as follows:

[0061] (1) 100g of high-silicon high-tungsten iron alloy enriched with precious metals is crushed to obtain high-silicon high-tungsten iron alloy powder (the mass fraction of powder with a particle size of less than 80 mesh is not less than 90.5%), under stirring conditions, the high-silicon high-tungsten iron alloy powder is added to dilute hydrochloric acid with a concentration of 1.5mol / L (the solid-liquid ratio g:mL of high-silicon high-tungsten iron alloy powder to dilute hydrochloric acid is 1:3), and the reaction is carried out at a temperature of 85℃ for 30min, then excess secondary oxidation recovered ferric chloride solid (1.5 times the theoretical amount) is added and the first-stage oxidation dissolution reaction is carried out at a temperature of 85℃ for 3.5h, and cooled to room temperature, solid-liquid separation is carried out to obtain 44.56g of insoluble residue A1 and filtrate B1, the insoluble residue A1 is washed to neutral with water; the weight loss in this dissolution stage is 55.44%, the total precious metal content is 14.26%, and the direct recovery rate of precious metals is 99.63%;

[0062] (2) insoluble residue A1 is added into a mechanical activation mill, a sodium hydroxide solution with a concentration of 4 mol / L is added (the solid-liquid ratio g:mL of insoluble residue A1 and sodium hydroxide solution is 1:3), and the second-stage activation leaching is carried out at a ball milling speed of 100 r / min and a temperature of 90°C for 80 min, then an equal volume of water is added for dilution, and 34.22 g of filter residue A2 and filtrate B2 are obtained through solid-liquid separation, and the insoluble residue A2 is washed to neutral with water; the weight loss of this dissolution stage is 10.34%, the total content of noble metals is 18.52%, and the direct recovery rate of noble metals is 99.77%;

[0063] (3) insoluble residue A2 is added into a stirring reaction kettle, a dilute hydrochloric acid with a concentration of 1.5 mol / L is added under the condition of stirring at a temperature of 90°C (the solid-liquid ratio g:mL of insoluble residue A2 and dilute hydrochloric acid is 1:3), and an excess of secondary oxidized recovered solid ferric chloride (1.5 times of the theoretical amount) is added for third-stage oxidation dissolution reaction for 3.5 h, and the reaction kettle is cooled to room temperature, and insoluble residue A3 and filtrate B3 are obtained through solid-liquid separation, and the insoluble residue A3 is washed to neutral with water and dried to obtain 21.85 g of noble metal enrichment residue; the weight loss of the iron alloy in this dissolution stage is 12.37%, the content of noble metals is 28.87%, and the direct recovery rate of noble metals is 99.79%;

[0064] The noble metal content of the noble metal enrichment residue obtained after three-stage iron dissolution in the example is analyzed and shown in Table 8; the noble metal content in the iron dissolution liquid is shown in Table 9;

[0065] Table 8 noble metal content in iron dissolution residue

[0066] ;

[0067] Table 9 noble metal content in iron dissolution liquid

[0068] ;

[0069] After three-stage dissolution in the example, the total direct recovery rate of noble metals including platinum, palladium, rhodium, iridium, ruthenium, gold and silver is 99.28%.

[0070] The specific embodiments of the application are described in detail above, but the application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the application.

Claims

1. A method for dissolving iron in a noble metal-enriched high-silicon-high-tungsten ferroalloy, characterized in that: The specific steps are as follows: (1) The high silicon and high tungsten ferroalloy enriched with precious metals is crushed to obtain high silicon and high tungsten ferroalloy powder. The high silicon and high tungsten ferroalloy powder is added to dilute hydrochloric acid under stirring conditions, and the reaction is carried out at a temperature of 80-90°C for 20-40 minutes. An excess of ferric chloride solid is then added to carry out the first stage of oxidative dissolution reaction. The mixture is cooled to room temperature, and solid-liquid separation is performed to obtain an insoluble residue A1 and a filtrate B1. The insoluble residue A1 is washed with water to a neutral state. (2) The insoluble residue A1 was added to a mechanical activation mill, and sodium hydroxide solution was added to perform the second stage of activation ball milling leaching for 60 to 120 minutes. Then, an equal volume of water was added for dilution, and solid-liquid separation was performed to obtain insoluble residue A2 and filtrate B2. The insoluble residue A2 was washed with water to neutrality; (3) The insoluble slag A2 was added to a stirred reactor, and dilute hydrochloric acid and excess ferric chloride solid were added at a temperature of 80-90°C and stirred for 3-4 hours to carry out the third stage of oxidative dissolution reaction. The slag was cooled to room temperature and the solid-liquid separation was performed to obtain the insoluble slag A3 and the filtrate B3. The insoluble slag A3 was washed with water to neutrality and dried to obtain the precious metal enriched slag.

2. The method for dissolving iron in a noble metal-enriched high-silicon-high-tungsten ferroalloy according to claim 1, characterized in that: The composition of the high silicon and high tungsten ferroalloy enriched with precious metals in step (1) is as follows, in percentage by mass: an iron content of not less than 65%, a silicon content of 8-13%, a tungsten content of 3-10%, a chromium content of 2-5%, a copper content of 1-4%, a nickel content of 0.5-2%, an iridium content of 0.5-1.5%, a platinum content of 1-2%, a palladium content of 1-2%, and a rhodium content of 0.5-2%.

3. The method for dissolving iron in a noble metal-enriched high-silicon-high-tungsten ferroalloy according to claim 1, characterized in that: In step (1), the mass proportion of the high silicon and high tungsten ferroalloy powder with a particle size less than 80 mesh is not less than 85%.

4. The method for dissolving iron in a noble metal-enriched high-silicon-high-tungsten ferroalloy according to claim 1, characterized in that: The concentration of the dilute hydrochloric acid in step (1) is 1.5-3.0 mol / L, and the solid-liquid ratio (g:mL) of the high-silicon-high-tungsten ferroalloy powder to the dilute hydrochloric acid is 1:3-5.

5. The method for dissolving iron in a noble metal-enriched high-silicon-high-tungsten ferroalloy according to claim 1, characterized in that: In step (1), the amount of ferric chloride solid added is 1.2 to 1.5 times the theoretical amount, the oxidation dissolution reaction temperature is 80 to 90° C., and the time is 3 to 5 hours.

6. The method for dissolving iron in a noble metal-enriched high-silicon-high-tungsten ferroalloy according to claim 1, characterized in that: In step (2), the concentration of the sodium hydroxide solution is 4-6 mol / L, the solid-liquid ratio (g:mL) of the insoluble residue A1 to the sodium hydroxide solution is 1:3-5, the activated ball mill leaching speed is 50-100 r / min, and the activated ball mill leaching temperature is 80-90°C.

7. The method for dissolving iron in a noble metal-enriched high-silicon-high-tungsten ferroalloy according to claim 1, characterized in that: The concentration of the dilute hydrochloric acid in step (3) is 1.5-3 mol / L, and the solid-liquid ratio (g:mL) of the insoluble residue A2 to the dilute hydrochloric acid is 1:3-5.

8. The method for dissolving iron in a noble metal-enriched high-silicon-high-tungsten ferroalloy according to claim 1, characterized in that: In step (3), the amount of ferric chloride solid added is 1.2 to 1.5 times the theoretical amount.