Preparation method of crude arsenic

Abstract

The invention belongs to the field of valuable metal recovery and arsenic harmless treatment, and particularly relates to a preparation method of crude arsenic. The preparation method of the crude arsenic comprises the following steps: putting an arsenic-containing material into a container of a vacuum distillation device, and sequentially carrying out vacuum distillation and condensation to obtain crude arsenic with the purity of 99% or above in an arsenic condensation area; the arsenic-containing material comprises a high-arsenic alloy; the temperature of vacuum distillation is 470-550 DEG C; and the arsenic condensation area is arranged at a position 40-50mm above the opening of the container. By adopting a vacuum distillation mode, arsenic is volatilized and condensed to a target area (an arsenic condensation area), and other elements are difficult to volatilize or condense to the area. The method is easy to operate, the vacuum distillation temperature is low, and the crude arsenic with the purity being 99% or above can be obtained only through one-time distillation. According to the method, crude arsenic easy to store is prepared while the high-arsenic alloy is treated, subsequent arsenic oxidation is avoided, and the method has the advantages of being environmentally friendly, efficient, high in recovery rate and free of chemical reagent consumption.

Description

Technical Field

[0001] This invention belongs to the field of valuable metal recycling and arsenic harmless treatment, specifically relating to a method for preparing crude arsenic. Background Technology

[0002] Precious lead is a product obtained through pyrometallurgical reduction smelting of lead and copper anode mud. High-arsenic alloys (arsenic content >20%) are byproducts of precious lead production during vacuum distillation, rich in valuable metals such as lead, antimony, and bismuth, and thus possess high value. However, high-arsenic alloys also contain arsenic, which, if improperly handled, can have a significant environmental impact. How to effectively extract valuable metals from high-arsenic alloys while simultaneously treating arsenic-containing waste harmlessly is a challenge facing the lead and copper metallurgical industries.

[0003] Precious lead, after being processed by vacuum vaporization, yields a high-arsenic alloy. If directly stored, this high-arsenic alloy, with an As content >20%, is easily oxidized to arsenic trioxide at room temperature and pressure, requiring stringent storage conditions. Converting it to metallic arsenic (gray arsenic) significantly improves its stability under normal conditions, making it easier to store safely. Related technologies disclose a method for extracting arsenic and silver from precious lead, employing a combination of primary vacuum distillation, staged condensation, and secondary vacuum distillation. The temperature of the first vacuum distillation is 1000~1100℃. This method is complex, involves high vacuum distillation temperatures, and can only process precious lead materials with low arsenic content (4~6% by mass). Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing crude arsenic. The preparation method of this invention is simple to operate, requiring only one vacuum distillation to obtain crude arsenic with a purity of over 99%, and the vacuum distillation temperature is low, making it suitable for processing high-arsenic alloys.

[0005] This invention provides a method for preparing crude arsenic, comprising the following steps: Arsenic-containing materials are placed in the container of a vacuum distillation apparatus for sequential vacuum distillation and condensation, and crude arsenic is obtained in the arsenic condensation zone; the purity of the crude arsenic is above 99%. The arsenic-containing material includes high-arsenic alloys or other arsenic-containing materials, and the other arsenic-containing materials include precious lead or precious bismuth. The temperature of the vacuum distillation is 470~550℃; the arsenic condensation zone is located 40~50mm above the container opening.

[0006] Preferably, the temperature of the vacuum distillation is 480~520℃.

[0007] Preferably, the vacuum degree of the vacuum distillation is 0.1~20 Pa.

[0008] Preferably, the heating rate from room temperature to the temperature of the vacuum distillation is 250~350℃ / h.

[0009] Preferably, the holding time for vacuum distillation is 30 to 150 minutes.

[0010] Preferably, the arsenic-containing material includes Pb, Sb, As, and Bi, and the sum of the mass contents of Pb, Sb, As, and Bi in the arsenic-containing material is >90%.

[0011] Preferably, the high-arsenic alloy comprises lead, antimony, bismuth, arsenic, silver, copper, gold, and iron; the high-arsenic alloy contains less than 10% antimony by mass, less than 45% lead by mass, less than 20% bismuth by mass, and more than 25% arsenic by mass.

[0012] Preferably, the condensation process further includes obtaining residues within the container, the residues comprising a lead-bismuth alloy.

[0013] Preferably, the lead-bismuth alloy contains >70% Pb by mass, and when the lead-bismuth alloy contains Sb, the sum of the mass contents of Pb, Bi and Sb is >80%.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing crude arsenic, comprising the following steps: placing arsenic-containing materials into a container of a vacuum distillation apparatus for sequential vacuum distillation and condensation, obtaining crude arsenic in the arsenic condensation zone; the purity of the crude arsenic is above 99%; the arsenic-containing materials include high-arsenic alloys or other arsenic-containing materials, the other arsenic-containing materials including precious lead or precious bismuth; the temperature of the vacuum distillation is 470~550℃; the arsenic condensation zone is located 40~50mm above the container opening.

[0015] This invention employs vacuum distillation to volatilize and condense arsenic into a target region (arsenic condensation zone), while other elements are difficult to volatilize or condense into this region, yielding crude arsenic with a purity of over 99%. This invention can process materials with varying arsenic contents. Furthermore, this invention is simple to operate, uses a low vacuum distillation temperature, and requires only one vacuum distillation to obtain crude arsenic with a purity of over 99%. This invention produces easily stored crude arsenic while processing high-arsenic alloys, avoiding subsequent arsenic oxidation, and offers advantages such as being green, efficient, having a high recovery rate, and requiring no chemical reagents.

[0016] The results of the examples show that, at a distillation temperature of 500℃, a vacuum degree of 5Pa, and a holding time of 60min, crude arsenic with a purity of 99.1% or 99.2% can be obtained at a distance of 40-50mm above the crucible opening. A lead-bismuth alloy residue is obtained inside the crucible, which can then be processed in a lead smelting system. The method for arsenic recovery in this invention features low vacuum distillation temperature, short time, and high efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a process flow diagram for preparing crude arsenic from high-arsenic alloys in the examples; Figure 2 This is a schematic diagram of the distillation crucible used in the examples. Detailed Implementation

[0019] This invention provides a method for preparing crude arsenic, comprising the following steps: Arsenic-containing materials are placed in the container of a vacuum distillation apparatus for sequential vacuum distillation and condensation, and crude arsenic is obtained in the arsenic condensation zone; the purity of the crude arsenic is above 99%. The arsenic-containing material includes high-arsenic alloys or other arsenic-containing materials, and the other arsenic-containing materials include precious lead or precious bismuth. The temperature of the vacuum distillation is 470~550℃; the arsenic condensation zone is located 40~50mm above the container opening.

[0020] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0021] In this invention, the container is preferably a crucible. The invention does not specifically limit the type of crucible; any crucible well-known to those skilled in the art for metal vacuum distillation can be used. In a specific embodiment, a distillation crucible is used, and the material of the distillation crucible is graphite. The vacuum distillation apparatus is preferably a vacuum furnace.

[0022] In this invention, the arsenic-containing material preferably includes Pb, Sb, As and Bi, and the sum of the mass contents of Pb, Sb, As and Bi in the arsenic-containing material is preferably >90%.

[0023] In this invention, the constituent elements of the high-arsenic alloy preferably include lead, antimony, bismuth, arsenic, silver, copper, gold, and iron; the oxygen content in the high-arsenic alloy is preferably less than 1%, the sulfur content is preferably less than 0.1%, the antimony content is preferably less than 10%, the lead content is preferably less than 45%, the bismuth content is preferably less than 20%, and the arsenic content is preferably greater than 25%. Specifically, the high-arsenic alloy may include the following components by mass: Pb 37.55%, As 45.05%, Sb 6.91%, Bi 6.24%, and other elements 4.25%; or it may include: Pb 31.67%, As 53.78%, Sb 5.23%, Bi 4.82%, and other elements 4.5%; the other elements mainly include oxygen and sulfur.

[0024] In this invention, the vacuum distillation temperature is preferably 480~520℃, specifically 480℃ or 500℃. This vacuum distillation temperature allows arsenic to volatilize while reducing the volatilization of other elements. The heating rate from room temperature to the vacuum distillation temperature is preferably 250~350℃ / h, specifically 300℃ / h. By controlling the heating rate within the above range, this invention avoids damage to the vacuum furnace due to excessively rapid heating.

[0025] In this invention, the vacuum degree of the vacuum distillation is preferably 0.1~20 Pa, specifically 5 Pa, 6 Pa, 7 Pa, 8 Pa, 9 Pa, or 10 Pa. The vacuum distillation equipment of this invention can withstand the vacuum degree required during the smelting process. The vacuum degree of the vacuum distillation described in this invention results in a significant difference in the saturated vapor pressure of arsenic compared to other elements, which is beneficial for the separation of arsenic from other components.

[0026] In this invention, the holding time for vacuum distillation is preferably 30-150 minutes, specifically 60 minutes, 75 minutes, or 90 minutes. This holding time allows for sufficient evaporation of arsenic.

[0027] In this invention, the condensation is preferably achieved by cooling and depressurizing the vacuum distillation apparatus. The order of cooling and depressurization is not particularly limited; a conventional cooling and pressure recovery sequence can be used to adjust the apparatus to room temperature and atmospheric pressure. The cooling method is preferably natural cooling. The pressure recovery method is not particularly limited; a method well-known to those skilled in the art can be used to release the negative pressure to atmospheric pressure.

[0028] In this invention, the arsenic condensation zone is located 40-50 mm above the container opening (the height of each vacuum chamber, i.e., the condensation zone, is 10 mm). This invention achieves the separation of arsenic from other components based on the differences in saturated vapor pressure and mean free path of the mixed gas components. Crude arsenic with a purity greater than 99% is obtained in the arsenic condensation zone, and the arsenic begins to condense at approximately 300°C.

[0029] In this invention, the condensation process further includes obtaining a residue in a container, the residue comprising a lead-bismuth alloy. The lead-bismuth alloy contains >70% Pb by mass, and when the lead-bismuth alloy contains Sb, the sum of the mass contents of Pb, Bi, and Sb is >80%. The lead-bismuth alloy preferably comprises the following components by mass: As <3%, Pb >70%, Sb >5%, Bi >10%; specifically, it may include: As 2.31%, Pb 72.2%, Sb 7.25%, Bi 13.26%, or As 1.87%, Pb 70.8%, Sb 7.76%, Bi 16.42%. The lead-bismuth alloy can be directly recycled during lead-bismuth smelting.

[0030] To further illustrate the present invention, the method for preparing crude arsenic provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0031] In the following examples or comparative examples, the "%" in the ingredients refers to mass percentages, and the other elements are mainly oxygen and sulfur.

[0032] The following is in accordance with Figure 1 The process flow diagram shown is used to prepare crude arsenic and lead-bismuth alloy; Figure 2 This is a schematic diagram of the distillation crucible (graphite crucible) used in the embodiment. The lower part of the diagram is the raw material chamber, the 0-30mm is the diffusion layer, and the upper part is the condensation plate, with each stage being 10mm.

[0033] Example 1 A method for preparing crude arsenic through green recycling of high-arsenic alloys includes the following steps: Take 1 kg of high-arsenic alloy (composition: Pb 37.55%, As 45.05%, Sb 6.91%, Bi 6.24%, other elements 4.25%), place it in a graphite crucible, and put it into a vacuum furnace. Heat to 500℃ at a rate of 300℃ / h, control the vacuum degree at 5 Pa, and set the arsenic condensation zone 40~50 mm above the crucible opening. Hold at this temperature for 60 min, then allow to cool naturally and return to normal pressure.

[0034] Crude arsenic (composition: As 99.1%, Pb 0.018%, Sb 0.5%, Bi 0.00075%) was obtained in the arsenic condensation zone, and the residue obtained in the crucible was a lead-bismuth alloy (composition: As 2.31%, Pb 72.2%, Sb 7.25%, Bi 13.26%). The yield of crude arsenic was 66.81%.

[0035] Example 2 A method for preparing crude arsenic through green recycling of high-arsenic alloys includes the following steps: Take 1 kg of high-arsenic alloy (composition: Pb 31.67%, As 53.78%, Sb 5.23%, Bi 4.82%, other elements 4.5%), place it in a graphite crucible, and put it into a vacuum furnace. Heat to 480℃ at a rate of 300℃ / h, control the vacuum degree at 5 Pa, and set the arsenic condensation zone 40~50 mm above the crucible opening. Hold at this temperature for 60 min, then allow to cool naturally and return to normal pressure.

[0036] Crude arsenic (composition: As 99.2%, Pb 0.002%, Sb 0.3%, Bi 0.001%) was obtained in the arsenic condensation zone, and the residue obtained in the crucible was a lead-bismuth alloy (composition: As 1.87%, Pb 70.8%, Sb 7.76%, Bi 16.42%). The yield of crude arsenic was 63.68%.

[0037] Comparative Example 1 A method for preparing crude arsenic through green recycling of high-arsenic alloys includes the following steps: Take 1 kg of high-arsenic alloy (composition: Pb 37.55%, As 45.05%, Sb 6.91%, Bi 6.24%, other elements 4.25%), place it in a graphite crucible, and put it into a vacuum furnace. Heat to 600℃ at a rate of 300℃ / h, maintain a vacuum of 5 Pa, and position the arsenic condensation zone 40-50 mm above the crucible opening. Hold at this temperature for 60 min, then allow to cool naturally and return to normal pressure.

[0038] Crude arsenic (composition: As 98.64%, Pb 0.0021%, Sb 0.76%, Bi 0.001%) was obtained in the arsenic condensation zone, and the residue obtained in the crucible was a lead-bismuth alloy (composition: As 0.92%, Pb 71.2%, Sb 8.15%, Bi 16.61%). The yield of crude arsenic was 58.23%.

[0039] Comparative Example 2 A method for preparing crude arsenic through green recycling of high-arsenic alloys includes the following steps: Take 1 kg of high-arsenic alloy (composition: Pb 37.55%, As 45.05%, Sb 6.91%, Bi 6.24%, other elements 4.25%), place it in a graphite crucible, and put it into a vacuum furnace. Heat to 700℃ at a rate of 300℃ / h, control the vacuum degree at 5 Pa, and set the arsenic condensation zone 40~50 mm above the crucible opening. Hold at this temperature for 60 min, then allow to cool naturally and return to normal pressure.

[0040] Crude arsenic (composition: As 97.89%, Pb 0.0015%, Sb 1.04%, Bi 0.015%) was obtained in the arsenic condensation zone, and the residue obtained in the crucible was a lead-bismuth alloy (composition: As 0.45%, Pb 73.8%, Sb 6.31%, Bi 15.69%). The yield of crude arsenic was 51.65%.

[0041] Comparative Example 3 A method for preparing crude arsenic through green recycling of high-arsenic alloys includes the following steps: Take 1 kg of high-arsenic alloy (composition: Pb 37.55%, As 45.05%, Sb 6.91%, Bi 6.24%, other elements 4.25%), place it in a graphite crucible, and put it into a vacuum furnace. Heat to 500℃ at a rate of 300℃ / h, maintain a vacuum of 5 Pa, and position the arsenic condensation zone 50-60 mm above the crucible opening. Hold at this temperature for 60 min, then allow to cool naturally and return to normal pressure.

[0042] Crude arsenic (composition: As 96.31%, Pb 0.032%, Sb 2.46%, Bi 0.0085%) was obtained in the arsenic condensation zone, and the residue obtained in the crucible was a lead-bismuth alloy (composition: As 1.13%, Pb 70.3%, Sb 10.46%, Bi 13.58%). The yield of crude arsenic was 48.13%.

[0043] Comparative Example 4 A method for preparing crude arsenic through green recycling of high-arsenic alloys includes the following steps: Take 1 kg of high-arsenic alloy (composition: Pb 37.55%, As 45.05%, Sb 6.91%, Bi 6.24%, other elements 4.25%), place it in a graphite crucible, and put it into a vacuum furnace. Heat to 500℃ at a rate of 300℃ / h, maintain a vacuum of 5 Pa, and position the arsenic condensation zone 30-40 mm above the crucible opening. Hold at this temperature for 60 min, then allow to cool naturally and return to atmospheric pressure.

[0044] Crude arsenic (composition: As 88.67%, Pb 0.039%, Sb 6.58%, Bi 0.021%) was obtained in the arsenic condensation zone, and the residue obtained in the crucible was a lead-bismuth alloy (composition: As 0.53%, Pb 73.45%, Sb 6.56%, Bi 15.44%). The yield of crude arsenic was 57.71%.

[0045] Comparative Example 5 Take 1 kg of high-arsenic alloy (composition: Pb 37.55%, As 45.05%, Sb 6.91%, Bi 6.24%, other elements 4.25%), place it in a graphite crucible, and put it into a vacuum furnace. The vacuum furnace is heated to 1000℃ at a rate of 400℃ / h, and the vacuum degree is controlled at 5 Pa. After holding at this temperature for 60 min, it is allowed to cool naturally and return to normal pressure.

[0046] Condensate was obtained in four condensation zones, as follows: The composition of the 30~40 mm fraction is: As 0.031%, Pb 78.14%, Sb 0.13%, Bi 18.94%; The composition of the 40-50 mm fraction is: As 1.38%, Pb 72.92%, Sb 2.47%, Bi 20.34%; The composition of the 50-60 mm fraction is: As 4.76%, Pb 70.19%, Sb 2.89%, Bi 21.95%; The composition of the 60-70mm fraction is: As 15.66%, Pb 57.14%, Sb 13.48%, Bi 10.31%; The residue obtained in the crucible was a lead-bismuth alloy (composition: As 0.0020%, Pb 81.77%, Sb 0.04%, Bi 17.81%). The total crude arsenic yield was 15.66% (total arsenic collected divided by the total arsenic volatilized). In this comparative example, due to the increased temperature, lead, bismuth, and antimony volatilized simultaneously in large quantities along with arsenic. Furthermore, arsenic has a much higher saturated vapor pressure than other elements, causing it to volatilize to higher altitudes or into the insulation felt, making it impossible to collect high-purity crude arsenic in the target condensation zone.

[0047] This invention involves vacuum distilling a high-arsenic alloy in a vacuum furnace. Crude arsenic is obtained in the arsenic condensation zone, while a lead-bismuth alloy residue is obtained in the crucible. Based on the differences in the saturated vapor pressure of the components, this invention establishes a dominant arsenic condensation zone. By employing vacuum distillation, arsenic volatilizes and condenses into this target zone, while other elements are difficult to volatilize or condense into this zone, resulting in crude arsenic with a purity of over 99%, thus avoiding subsequent arsenic oxidation. Results show that at a distillation temperature of 500℃, a vacuum degree of 5 Pa, and a holding time of 60 min, crude arsenic with a purity of 99.1% or 99.2% can be obtained at a distance of 40-50 mm above the crucible opening, with a lead-bismuth alloy residue remaining in the evaporation crucible. This invention simultaneously processes high-arsenic alloys and produces easily stored crude arsenic, offering advantages such as being green and efficient, having a high recovery rate, and requiring no chemical reagents.

[0048] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing crude arsenic, characterized in that, Includes the following steps: Arsenic-containing materials are placed in the container of a vacuum distillation apparatus for sequential vacuum distillation and condensation, and crude arsenic is obtained in the arsenic condensation zone; the purity of the crude arsenic is above 99%. The arsenic-containing material includes high-arsenic alloys or other arsenic-containing materials, and the other arsenic-containing materials include precious lead or precious bismuth. The temperature of the vacuum distillation is 470~550℃; the arsenic condensation zone is located 40~50mm above the container opening.

2. The preparation method according to claim 1, characterized in that, The temperature of the vacuum distillation is 480~520℃.

3. The preparation method according to claim 1 or 2, characterized in that, The vacuum degree of the vacuum distillation is 0.1~20 Pa.

4. The preparation method according to claim 1 or 2, characterized in that, The heating rate from room temperature to the vacuum distillation temperature is 250~350℃ / h.

5. The preparation method according to claim 1 or 2, characterized in that, The holding time for vacuum distillation is 30~150 min.

6. The preparation method according to claim 1, characterized in that, The arsenic-containing material includes Pb, Sb, As, and Bi, and the sum of the mass contents of Pb, Sb, As, and Bi in the arsenic-containing material is >90%.

7. The preparation method according to claim 1, characterized in that, The high-arsenic alloy comprises lead, antimony, bismuth, arsenic, silver, copper, gold, and iron; the antimony content in the high-arsenic alloy is less than 10%, the lead content is less than 45%, the bismuth content is less than 20%, and the arsenic content is greater than 25%.

8. The preparation method according to claim 6 or 7, characterized in that, The condensation process also includes obtaining residues within the container, which include a lead-bismuth alloy.

9. The preparation method according to claim 8, characterized in that, The lead-bismuth alloy contains Pb with a mass content >70%, and when the lead-bismuth alloy contains Sb, the sum of the mass contents of Pb, Bi and Sb is >80%.

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