CN118813967A - A method for recovering valuable metals and arsenic in arsenic-containing copper ash - Google Patents

Abstract

The invention discloses a recycling method of valuable metals and arsenic in arsenic-containing copper ash, and belongs to the technical field of treatment of the arsenic-containing copper ash. The invention takes the arsenic-containing copper ash produced in the copper smelting field as a treatment object, and mixes the arsenic-containing copper ash, iron powder and lime powder to prepare bricks; then adding the brick materials into a smelting furnace; simultaneously blowing oxygen-enriched air, adding coke and quartz, and reacting in high-temperature reducing gas to generate dust-containing flue gas and high-temperature eutectic; finally, the high-temperature eutectic flows into a molten pool and then is subjected to sedimentation separation, wherein slag, lead matte, arsenic iron alloy and crude lead are sequentially arranged from top to bottom. The invention realizes the comprehensive and efficient recovery of valuable metals such as copper, lead, silver, gold, bismuth, tin and the like through high-temperature reduction smelting, converts arsenic in the valuable metals into high-purity arsenic-iron alloy capable of being recycled, is hopeful to fundamentally solve the industrial problems of arsenic treatment and recycling, and simultaneously realizes the comprehensive and efficient recovery of valuable metals in the arsenic-containing copper ash and recycling of arsenic.

Description

A method for recovering valuable metals and arsenic in arsenic-containing copper ash

Technical Field

The invention belongs to the technical field of arsenic-containing copper ash treatment, and in particular relates to a method for recovering and utilizing valuable metals and arsenic in arsenic-containing copper ash.

Background Art

Currently, about 80% of copper in the world is produced by pyrometallurgical smelting. The copper ash produced during the pyrometallurgical copper smelting process is rich in copper, lead, zinc, silver, bismuth, tin and other valuable metals, as well as 3% to 15% arsenic. Improper disposal will pose a risk of heavy metal and arsenic pollution.

At present, the extraction of valuable metals from copper smelting ash and the separation and solidification of arsenic are mainly carried out at home and abroad by pyrometallurgical or hydrometallurgical processes. Among them, the pyrometallurgical treatment of copper ash is to use the characteristics of arsenic trioxide in the ash to be volatile, and roast it under medium and low temperature conditions to obtain de-arsenicized ash and crude arsenic trioxide ash. The arsenic volatilization rate in this process is about 80%, the separation is not thorough, and there is no safe and effective disposal method for the highly toxic crude arsenic trioxide dust. In the wet treatment of copper ash, arsenic in the copper ash enters the leaching solution together with copper, zinc, indium, etc. The subsequent arsenic purification and separation process is complicated, and a large amount of hazardous waste arsenic slag such as arsenic sulfide slag, calcium arsenate slag, and iron arsenate slag is produced. The hazardous waste arsenic slag produced needs to be harmlessly treated.

In summary, the current treatment process for arsenic-containing copper ash still has the following shortcomings: (1) The separation of valuable metals and arsenic is not complete, which affects the further recycling of valuable metals and product quality. (2) The existence form of arsenic is converted from arsenic trioxide in the smoke to secondary hazardous waste arsenic slag such as crude arsenic trioxide, arsenic sulfide, calcium arsenate, and arsenic acid slag that are easy to make drugs.

Summary of the invention

In view of the shortcomings of the above-mentioned prior art, the present invention provides a method for recycling valuable metals and arsenic in arsenic-containing copper ash. The present invention takes arsenic-containing copper ash produced in the copper smelting field as the processing object, realizes the comprehensive and efficient recovery of valuable metals such as copper, lead, silver, gold, bismuth, tin, etc. through high-temperature reduction smelting, and converts the arsenic therein into a high-purity arsenic-iron alloy containing 35% to 45% arsenic and 50% to 68% iron that can be recycled, which is expected to fundamentally solve the industry problems of arsenic treatment and resource utilization, and at the same time realize the comprehensive and efficient recovery of valuable metals in arsenic-containing copper ash and the resource utilization of arsenic.

To achieve the above object, the technical solution adopted by the present invention is:

A method for recovering valuable metals and arsenic in arsenic-containing copper ash comprises the following steps:

(1) Mixing arsenic copper fly ash, iron powder and lime powder to make bricks, and controlling the water content of the bricks to be less than 8%;

(2) weighing the bricks prepared in step (1) and adding them into a smelting furnace; at the same time, blowing in oxygen-enriched air and coke, adding quartz, and reacting in a high temperature of 1100° C. to 1400° C. in a reducing atmosphere to generate dust-containing flue gas and a high-temperature eutectic;

(3) After the high-temperature eutectic flows into the molten pool, it is subjected to sedimentation separation, and the order from top to bottom is slag, lead matte, arsenic-iron alloy, and crude lead, wherein the crude lead is discharged through the discharge port; the high-temperature melt containing slag, lead matte, and arsenic-iron alloy is discharged into a slag bag, and the slag in the slag bag is overflowed and then quenched with water, and the lead matte melt on the upper layer and the arsenic-iron alloy melt on the lower layer are cooled and separated to obtain lead matte and arsenic-iron alloy.

As a preferred embodiment of the present invention, the mass of the iron powder is 20%-35% of the mass of the arsenic-containing copper fly ash.

The oxygen-enriched air refers to the air in which the oxygen concentration in a certain space is greater than 21%.

As a preferred embodiment of the present invention, the mass of the coke is 15%-25% of the mass of the arsenic-copper fly ash.

As a preferred embodiment of the present invention, in the step (2), the dust-containing flue gas is sequentially subjected to cooling, dust collection, and tail gas absorption to obtain smelting dust, and the smelting dust is returned to the step (1) and mixed with iron powder and lime powder to make bricks.

As a preferred embodiment of the present invention, the mass percentage of lead in the crude lead is above 90%. The crude lead can be used as a raw material for producing electrolytic lead and recovering valuable elements such as silver, gold, bismuth, etc.

As a preferred embodiment of the present invention, the lead matte comprises the following elements in percentage by mass: 10% to 30% copper, 7% to 11% lead, 1% to 3.5% bismuth, and 19% to 30% sulfur. The lead matte enters the pyrometallurgical copper smelting system to further recover the valuable elements (copper, lead, bismuth) therein.

As a preferred embodiment of the present invention, the ferroarsenic alloy comprises the following elements in percentage by mass: 35% to 45% arsenic and 50% to 68% iron. The ferroarsenic alloy has the characteristics of stable properties and high specific gravity, and can be used as a counterweight raw material for large-scale resource utilization.

As a preferred embodiment of the present invention, the mass percentage of zinc in the slag is 9%-19%. The slag is further treated with a volatilization kiln to recover the zinc therein and produce iron powder, which is returned to the batching process in step (1).

Compared with the prior art, the present invention has the following beneficial effects:

The present invention can simultaneously realize the comprehensive and efficient recovery of valuable metals in arsenic-containing copper ash and the resource utilization of harmful element arsenic, and realize the clean and efficient recovery and utilization of valuable and harmful elements in arsenic-containing ash. After high-temperature reduction and smelting, arsenic-containing copper ash produces intermediate products such as crude lead, lead matte, smelting dust, arsenic-iron alloy products and slag, and valuable metals are highly selectively enriched in the intermediate products. Among them, the recovery rate of lead and copper is more than 98%, the recovery rate of bismuth is greater than 90.5%, and the enrichment rate of silver and gold is more than 99%. More than 85% of zinc is enriched in the slag; the output arsenic-containing smelting dust is returned to the batching, realizing the closed-loop circulation of arsenic in the system without the output of hazardous waste; arsenic is 100% productized in the form of arsenic-iron alloy, and the generated arsenic-iron alloy has the excellent characteristics of stable properties and high specific gravity, which can be used in the field of industrial counterweights. At the same time, since arsenic is mainly recovered as arsenic-iron alloy, the amount of arsenic in the intermediate products containing valuable metals is greatly reduced, which can fundamentally solve the industry problems of arsenic pollution and arsenic treatment that have long plagued the industrial field. In addition, compared with other current processes for treating arsenic-containing copper ash, the present invention has the technical advantages of fully utilizing valuable and harmful elements, not adding any secondary hazardous waste, having a clean and efficient process, having a high comprehensive recovery rate of valuable metals, and being able to realize resource utilization of the harmful element arsenic.

DETAILED DESCRIPTION

In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

A method for recovering valuable metals and arsenic in arsenic-containing copper ash, comprising the following contents:

(1) Ingredients and brick making: Arsenic copper fly ash, iron powder and lime powder are mixed to make bricks, wherein the amount of iron powder added is 20% to 35% of the mass of the arsenic copper fly ash. The bricks are left for a period of time to reduce the water content to below 8%.

(2) Reduction smelting: The precipitation brick material of step (1) is weighed by a weighing device and continuously added into the smelting furnace through the furnace top charging port; at the same time, oxygen-enriched air and coke containing 15% to 25% of the mass of arsenic copper ash are blown in through the side tuyere of the smelting furnace, and quartz is added from the smelting furnace charging port. In a high-temperature reducing atmosphere of 1100°C to 1400°C, the reactants undergo a chemical reaction to generate dust-containing flue gas and a high-temperature eutectic of crude lead, lead matte, arsenic iron alloy, slag, etc. The dust-containing flue gas is subjected to a cooling-dust collection-tail gas absorption process to obtain smelting dust, which is returned to the ingredients in step (1).

The main function of coke is to provide the heat required for the reaction and the reducing agent for the reduction reaction. In the reduction smelting process, a series of chemical reactions mainly occur, such as coke combustion, oxide reduction, crude lead production, lead matte production, arsenic iron alloy production, and slag production. At a smelting temperature of 1100°C to 1400°C, As ₂ O ₃ in gaseous form has strong volatility. The gaseous As ₂ O ₃ in the rising process contacts coke or CO in a strong reducing atmosphere and is immediately reduced to gaseous elemental arsenic. The gaseous elemental arsenic is adsorbed on the surface of the solid or semi-solid furnace charge, continuously falls into the molten pool, and reacts with the iron droplets therein to form arsenic iron alloy. More than 90% of the arsenic in the raw material of step (1) is recovered as arsenic iron alloy during the smelting process, and about 10% of the arsenic enters the dusty flue gas and returns to the batching of step (1), thereby basically achieving 100% of the arsenic being recovered as arsenic iron alloy, greatly reducing the amount of arsenic in the intermediate product containing valuable metals, and the subsequent recovery of valuable metals is basically not affected by arsenic. Most of the iron powder added in the raw materials forms arsenic-iron alloy, and a small part is oxidized into ferrous oxide and then forms a ternary slag system with quartz and lime powder, thereby reducing slag temperature and carbon consumption under the condition of ensuring slag fluidity.

(3) Sedimentation and separation: After various high-temperature eutectics such as crude lead, lead matte, arsenic-iron alloy, and slag flow into the molten pool, the unfinished crude lead, lead matte, arsenic-iron alloy, and slag of step (2) are continued to undergo various reactions and are separated by sedimentation in the molten pool at the bottom of the furnace according to the difference in specific gravity. From top to bottom, they are slag, lead matte, arsenic-iron alloy, and crude lead. The crude lead melt is discharged through a separate discharge port and further recycled; the high-temperature melts of slag, lead matte, and arsenic-iron alloy flow through the same external discharge port into two stepped slag bags. The slag in the slag bag overflows and is quenched in water. The upper layer of the lead matte melt and the lower layer of the arsenic-iron alloy melt are cooled and separated to obtain lead matte and arsenic-iron alloy.

More than 90% of the lead and bismuth, and more than 99% of the silver and gold in the raw materials are enriched in crude lead. Since their specific gravity is greater than that of other smelting products, they are solidly settled at the bottom of the furnace. They can be discharged separately through the lead port set at the bottom of the furnace, and become the raw materials for further recovery of high-quality lead, bismuth, gold and silver. The slag is a ternary eutectic of ferrous oxide, quartz and lime powder. More than 85% of the zinc in the raw materials is enriched in it. The slag contains 9% to 19% zinc. It can be further processed by a volatilization kiln to recover the zinc and produce iron powder, which is returned to the batching process. 100% of the arsenic in the raw materials is recovered as arsenic-iron alloy; more than 98% of the copper in the raw materials is enriched in lead matte, which is a eutectic of lead sulfide and copper sulfide, and is the raw material for further extraction of copper and comprehensive recovery of lead.

Example 1

A method for recovering valuable metals and arsenic in arsenic-containing copper ash comprises the following steps:

(1) Ingredients and brick making: The arsenic-copper fly ash and iron powder as shown in Table 1 and lime powder added according to the slag making process requirements are mixed to make bricks. The bricks are left for a period of time to reduce their water content to about 7%. The composition of the bricks before entering the furnace is shown in Table 2.

(2) Reduction smelting: Weigh the dewatered brick material from step (1) and continuously add it into the smelting furnace through the top charging port; at the same time, blow coke and oxygen-enriched air with an oxygen consumption of 1.1 times the coke combustion through the side tuyere of the smelting furnace, and add quartz from the charging port of the smelting furnace. In a high-temperature reducing atmosphere at 1100°C to 1400°C, the reactants undergo chemical reactions to generate dust-containing flue gas and a high-temperature eutectic of crude lead, lead matte, arsenic-iron alloy, slag, etc.

(3) Sedimentation and separation: After various high-temperature eutectics such as crude lead, lead matte, arsenic iron alloy, and slag flow into the molten pool, they continue the various reactions of making crude lead, lead matte, arsenic iron alloy, and slag that were not completed in step (2) and are separated by sedimentation in the molten pool at the bottom of the furnace according to the difference in specific gravity. From top to bottom, they are slag, lead matte, arsenic iron alloy, and crude lead. The crude lead melt is discharged through a separate discharge port and further recycled; the high-temperature melts of slag, lead matte, and arsenic iron alloy flow through the same external discharge port into two stepped slag bags. The slag in the slag bag overflows and is quenched with water. The upper layer of lead matte melt and the lower layer of arsenic iron alloy melt are cooled and separated to obtain lead matte and arsenic iron alloy.

The method for recovering and utilizing valuable metals and arsenic in arsenic-containing copper fly ash is operated continuously for 120 hours, during which the processing capacity of arsenic-containing fly ash is 150 tons/day, the proportion of iron powder added is 45 tons/day, the proportion of lime powder added is 10 tons/day, the quartz consumption is 9 tons/day, and the coke consumption is 15 tons/day.

25.9 tons of crude lead are produced per day, and its composition is shown in Table 3; 90 tons of lead matte are produced per day, and the lead matte contains the following mass percentages: copper 15.0%, lead 10.8%, bismuth 1.1%, sulfur 25.5%; 21.4 tons of arsenic-iron alloy are produced per day, and the arsenic-iron alloy contains the following mass percentages: arsenic 41% and iron 55%; 70.7 tons of water-quenched slag are produced per day, and its composition is shown in Table 4.

After the arsenic-containing copper fly ash is treated by this embodiment, the recovery rates of valuable elements are: 98.0% for copper, 98.1% for lead, 90.6% for bismuth, 99% for gold, and 99% for silver; 85.5% for zinc is enriched in the slag; 90% for arsenic is converted into arsenic-iron alloy products; and the gold and silver in the crude lead are enriched 5.8 times as much as that in the raw material, reaching 2.9 g/t and 1080 g/t, respectively.

The arsenic recovery rate described in this embodiment is the one-way recovery rate (direct recovery rate) of arsenic, that is, the recovery rate of one-way smelting. In the reduction smelting step, the arsenic that is not converted into arsenic-iron alloy enters the smoke and eventually returns to step (1), thereby basically achieving 100% recovery of arsenic as arsenic-iron alloy.

Table 1 Composition of Arsenic-containing Copper Smoke Dust (mass percentage, %)

Table 2 Composition of dewatering brick materials entering the furnace (mass percentage, %)

Table 3 Crude lead product composition (mass percentage, %)

element Pb Bi Ag, g/t Au，g/t Sn content 91.0 2.3 1080 2.9 0.1

Table 4 Water quenching slag composition (mass percentage, %)

element FeO SiO ₂ CaO Cu Pb Bi Sn Zn content 46.1 12.0 13.1 0.2 0.3 0.1 0.07 9.0

Example 2

A method for recovering valuable metals and arsenic in arsenic-containing copper ash comprises the following steps:

(1) Ingredients and brick making: The arsenic-copper fly ash, iron powder and lime powder added according to the slag making process requirements as shown in Table 5 are mixed to make bricks. The bricks are left for a period of time to reduce their moisture content to about 6%. The composition of the bricks before entering the furnace is shown in Table 6.

(2) Reduction smelting: Weigh the dewatered brick material from step (1) and continuously add it into the smelting furnace through the top charging port; at the same time, blow coke and oxygen-enriched air with an oxygen consumption of 1.3 times that of coke combustion into the smelting furnace through the side tuyere of the smelting furnace, and add quartz from the charging port of the smelting furnace. In a high-temperature reducing atmosphere at 1100°C to 1400°C, the reactants undergo chemical reactions to generate dust-containing flue gas and a high-temperature eutectic of crude lead, lead matte, arsenic-iron alloy, slag, etc.

(3) Sedimentation and separation: After various high-temperature eutectics such as crude lead, lead matte, arsenic iron alloy, and slag flow into the molten pool, they continue the various reactions of making crude lead, lead matte, arsenic iron alloy, and slag that were not completed in step (2) and are separated by sedimentation in the molten pool at the bottom of the furnace according to the difference in specific gravity. From top to bottom, they are slag, lead matte, arsenic iron alloy, and crude lead. The crude lead melt is discharged through a separate discharge port and further recycled; the high-temperature melts of slag, lead matte, and arsenic iron alloy flow through the same external discharge port into two stepped slag bags. The slag in the slag bag overflows and is quenched with water. The upper layer of lead matte melt and the lower layer of arsenic iron alloy melt are cooled and separated to obtain lead matte and arsenic iron alloy.

The method for recovering valuable metals and arsenic in arsenic-containing copper fly ash is operated continuously for 120 hours, during which the arsenic-containing fly ash processing capacity is 100 tons/day, the iron powder addition ratio is 20 tons/day, the lime powder addition ratio is 7 tons/day, the quartz consumption is 6 tons/day, and the coke consumption is 15 tons/day.

15.2 tons of crude lead are produced per day, and its composition is shown in Table 7; 54 tons of lead matte are produced per day, and the lead matte contains the following mass percentages: copper 10.0%, lead 8.0%, bismuth 5.6%, sulfur 19.4%; 16.3 tons of arsenic-iron alloy are produced per day, and the arsenic-iron alloy contains the following mass percentages: arsenic 45% and iron 50%; 36.2 tons of water-quenched slag are produced per day, and its composition is shown in Table 8.

After the arsenic-containing copper fly ash is treated by this embodiment, the recovery rates of valuable elements are: 98.5% for copper, 98.8% for lead, 91.2% for bismuth, 99% for gold, and 99% for silver; 86.2% for zinc is enriched in the slag; 91.4% for arsenic is converted into arsenic-iron alloy products; and the gold and silver in the crude lead are enriched 6.6 times as much as that in the raw material, reaching 10.6 g/t and 1840 g/t, respectively.

The arsenic recovery rate described in this embodiment is the one-way recovery rate (direct recovery rate) of arsenic, that is, the recovery rate of one-way smelting. In the reduction smelting step, the arsenic that is not converted into arsenic-iron alloy enters the smoke and eventually returns to step (1), thereby basically achieving 100% recovery of arsenic as arsenic-iron alloy.

Table 5 Composition of Arsenic-containing Copper Smoke Dust (mass percentage, %)

Table 6 Composition of dewatering brick materials entering the furnace (mass percentage, %)

Table 7 Crude lead product composition (mass percentage, %)

element Pb Bi Ag, g/t Au，g/t Sn content 91.5 7.1 1840 10.5 0.08

Table 8 Water quenching slag composition (mass percentage, %)

element FeO SiO ₂ CaO Cu Pb Bi Sn Zn content 31.7 13.4 15.1 0.17 0.34 0.09 0.05 19.0

Example 3

A method for recovering valuable metals and arsenic in arsenic-containing copper ash comprises the following steps:

(1) Ingredients and brick making: The arsenic-copper fly ash, iron powder and lime powder added according to the slag making process requirements as shown in Table 9 are mixed to make bricks. The bricks are left for a period of time to reduce their moisture content to about 6.5%. The composition of the bricks before entering the furnace is shown in Table 10.

(2) Reduction smelting: Weigh the dewatered brick material from step (1) and continuously add it into the smelting furnace through the top charging port; at the same time, blow coke and oxygen-enriched air with an oxygen consumption of 1.2 times that of coke combustion through the side tuyere of the smelting furnace, and add quartz from the charging port of the smelting furnace. In a high-temperature reducing atmosphere at 1100°C to 1400°C, the reactants undergo chemical reactions to generate dust-containing flue gas and a high-temperature eutectic of crude lead, lead matte, arsenic-iron alloy, slag, etc.

(3) Sedimentation and separation: After various high-temperature eutectics such as crude lead, lead matte, arsenic iron alloy, and slag flow into the molten pool, they continue the various reactions of making crude lead, lead matte, arsenic iron alloy, and slag that were not completed in step (2) and are separated by sedimentation in the molten pool at the bottom of the furnace according to the difference in specific gravity. From top to bottom, they are slag, lead matte, arsenic iron alloy, and crude lead. The crude lead melt is discharged through a separate discharge port and further recycled; the high-temperature melts of slag, lead matte, and arsenic iron alloy flow through the same external discharge port into two stepped slag bags. The slag in the slag bag overflows and is quenched with water. The upper layer of lead matte melt and the lower layer of arsenic iron alloy melt are cooled and separated to obtain lead matte and arsenic iron alloy.

The method for recovering and utilizing valuable metals and arsenic in arsenic-containing copper fly ash is operated continuously for 120 hours, during which the arsenic-containing fly ash processing capacity is 120 tons/day, the iron powder addition ratio is 42 tons/day, the lime powder addition ratio is 7 tons/day, the quartz consumption is 8 tons/day, and the coke consumption is 24 tons/day.

20.8 tons of crude lead are produced every day, and its composition is shown in Table 11; 57.6 tons of lead matte are produced every day, and the lead matte contains the following mass percentages: 30.2% copper, 7.3% lead, 1.5% bismuth, and 29.9% sulfur; 47.6 tons of arsenic-iron alloy are produced every day, and the arsenic-iron alloy contains the following mass percentages: 35% arsenic and 50% iron; 46.6 tons of water-quenched slag are produced every day, and its composition is shown in Table 12.

After the arsenic-containing copper fly ash is treated by this embodiment, the recovery rates of valuable elements are: 98.6% for copper, 98.3% for lead, 91.7% for bismuth, 99% for gold, and 99% for silver; 85.9% of zinc is enriched in the slag; 90.9% of arsenic is converted into arsenic-iron alloy products; and the gold and silver in the crude lead are enriched 5.8 times as much as that in the raw material, reaching 5.2 g/t and 1150 g/t, respectively.

The arsenic recovery rate described in this embodiment is the one-way recovery rate (direct recovery rate) of arsenic, that is, the recovery rate of one-way smelting. In the reduction smelting step, the arsenic that is not converted into arsenic-iron alloy enters the smoke and eventually returns to step (1), thereby basically achieving 100% recovery of arsenic as arsenic-iron alloy.

Table 9 Composition of Arsenic-containing Copper Smoke Dust (mass percentage, %)

Table 10 Composition of dewatering brick materials entering the furnace (mass percentage, %)

Table 11 Crude lead product composition (mass percentage, %)

element Pb Bi Ag, g/t Au，g/t Sn content 90.3 6.7 1150 5.2 0.1

Table 12 Water quenching slag composition (mass percentage, %)

element FeO SiO ₂ CaO Cu Pb Bi Sn Zn content 50.2 15.1 14.4 0.3 0.5 0.1 0.06 12.2

Comparative Example 1

The only difference between the method for recycling valuable metals and arsenic in arsenic-containing copper ash in this comparative example and Example 2 is that in step (1), no iron powder is added, and the composition of the dewatering brick material entering the furnace is as shown in Table 13.

22.2 tons of crude lead are produced every day, and its composition is shown in Table 14; 54 tons of lead matte are produced every day, and the lead matte contains the following mass percentages: copper 10.0%, lead 8.0%, bismuth 5.6%, sulfur 19.4%; 23.4 tons of water-quenched slag are produced every day, and its composition is shown in Table 15.

After treating arsenic-containing copper ash with this comparative example, the recovery rates of valuable elements are: 98.5% copper, 98.8% lead, 91.2% bismuth, 99% gold, and 99% silver; 75.1% zinc is enriched in the slag; no arsenic-iron alloy products are produced; gold and silver in crude lead are 4.5 times more enriched than the raw material, reaching 7.2g/t and 1260g/t respectively. More than 85% of arsenic enters the crude lead, resulting in the lead and bismuth contents in the crude lead being reduced from 91.5% and 7.1% to 62.3% and 4.8% respectively. At the same time, the crude lead contains arsenic as high as 30.9%, and further recovery of valuable metals in the crude lead requires additional processing steps.

Table 13 Composition of dewatering brick materials entering the furnace (mass percentage, %)

Table 14 Crude lead product composition (mass percentage, %)

element Pb As Bi Ag, g/t Au，g/t Sn content 62.3 30.9 4.8 1260 7.2 0.07

Table 15 Water quenching slag composition (mass percentage, %)

element FeO SiO ₂ CaO Cu Pb Bi Sn Zn content 27.8 25.6 26.7 0.3 0.4 0.08 0.07 25.7

Comparative Example 2

The only difference between the method for recycling valuable metals and arsenic in arsenic-containing copper ash in this comparative example and Example 3 is that in step (1), the iron powder is replaced by iron oxide, and the composition of the dewatering brick material entering the furnace is as shown in Table 10.

The method for recovering and utilizing valuable metals and arsenic in arsenic-containing copper fly ash is operated continuously for 120 hours, during which the arsenic-containing fly ash processing capacity is 120 tons/day, the iron oxide addition ratio is 54 tons/day, the lime powder addition ratio is 7 tons/day, the quartz consumption is 8 tons/day, and the coke consumption is 24 tons/day.

26.9 tons of crude lead are produced per day, and its composition is shown in Table 16; 60 tons of lead matte are produced per day, and the lead matte contains the following mass percentages: 28.99% copper, 7.0% lead, 1.7% bismuth, 28.7% sulfur, and 3.0% arsenic; 104.3 tons of water-quenched slag are produced per day, and its composition is shown in Table 17.

After using this comparative example to treat arsenic-containing copper ash, no arsenic-iron alloy is produced. About 50% of the arsenic in the raw material enters the smelting smoke, 25% enters the crude lead, 10% enters the matte, and 15% enters the slag. As a result, the lead, bismuth, silver, and gold grades in the crude lead dropped from 90.3%, 6.7%, 1150g/t, and 5.2g/t to 69.8%, 5.22%, 890g/t, and 4g/t, respectively. The arsenic content is as high as 17.1%. Due to the high arsenic content in the crude lead, the subsequent recovery of lead and valuable metals in the crude lead is suppressed. The arsenic content in the lead matte is as high as 3%, which is difficult to further process; the arsenic content in the slag is as high as 3.6%, which affects its further resource utilization. The iron oxide added in the batching stage almost enters the water-quenched slag, which increases unnecessary iron material consumption and affects production efficiency.

Table 16 Crude lead product composition (mass percentage, %)

element Pb As Bi Ag, g/t Au，g/t Sn content 69.8 5.22 890 4.0 0.07 17.1%

Table 17 Water quenching slag composition (mass percentage, %)

element FeO SiO ₂ CaO Cu Pb Bi Sn Zn As content 74.2 6.74 6.43 0.1 0.2 0.04 0.02 5.4 3.6

In summary, in step (1) of the present invention, whether ferrous oxide, ferric oxide or magnetic iron is used, since high-purity arsenic-iron alloy cannot be generated, the arsenic content in crude lead, lead matte and slag will exceed the standard, which is not conducive to the further recovery of valuable metals and the production of arsenic-iron alloy cannot be achieved, thus making it difficult to achieve the recovery and utilization of the toxic element arsenic.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims (8)

1. A method for recovering valuable metals and arsenic in arsenic-containing copper ash, characterized in that it comprises the following steps: (1) Mixing arsenic copper fly ash, iron powder and lime powder to make bricks, and controlling the water content of the bricks to be less than 8%; (2) weighing the bricks prepared in step (1) and adding them into a smelting furnace; at the same time, blowing in oxygen-enriched air and coke, adding quartz, and reacting in a high temperature of 1100° C. to 1400° C. in a reducing atmosphere to generate dust-containing flue gas and a high-temperature eutectic; (3) After the high-temperature eutectic flows into the molten pool, it is subjected to sedimentation separation, and the order from top to bottom is slag, lead matte, arsenic-iron alloy, and crude lead, wherein the crude lead is discharged through the discharge port; the high-temperature melt containing slag, lead matte, and arsenic-iron alloy is discharged into a slag bag, and the slag in the slag bag is overflowed and then quenched with water, and the lead matte melt on the upper layer and the arsenic-iron alloy melt on the lower layer are cooled and separated to obtain lead matte and arsenic-iron alloy. 2. The method for recycling valuable metals and arsenic in arsenic-containing copper ash as claimed in claim 1, characterized in that the mass of the iron powder is 20%-35% of the mass of the arsenic-containing copper ash. 3. The method for recycling valuable metals and arsenic in arsenic-containing copper ash as claimed in claim 1, characterized in that the mass of the coke is 15%-25% of the mass of the arsenic-containing copper ash. 4. The method for recycling valuable metals and arsenic in arsenic-containing copper ash as claimed in claim 1, characterized in that in the step (2), the dust-containing flue gas is sequentially subjected to cooling, dust collection, and tail gas absorption treatment to obtain smelting dust, and the smelting dust is returned to step (1) for mixing and brick making. 5. The method for recycling valuable metals and arsenic in arsenic-containing copper ash as claimed in claim 1, characterized in that the mass percentage of lead in the crude lead is more than 90%. 6. The method for recycling valuable metals and arsenic in arsenic-containing copper ash as described in claim 1 is characterized in that the lead matte includes the following elements in percentage by mass: 10% to 30% copper, 7% to 11% lead, 1% to 3.5% bismuth, and 19% to 30% sulfur. 7. The method for recycling valuable metals and arsenic in arsenic-containing copper ash as claimed in claim 1, characterized in that the arsenic-iron alloy comprises the following elements in percentage by mass: 35% to 45% arsenic and 50% to 68% iron. 8. The method for recycling valuable metals and arsenic in arsenic-containing copper ash according to claim 1, characterized in that the mass percentage of zinc in the slag is 9%-19%.