JPH04304327A - Treatment of decopperized dross - Google Patents

Abstract

PURPOSE:To easily recover tin in a high yield by treating a decopperized dross with a hydrochloric acid, selectively leaching tin, separating the leaching solution, dipping aluminum pieces into this solution and precipitating metallic tin. CONSTITUTION:The decopperized dross containing of metallic tin and copper as main components is dipped into the conc. hydrochloric acid at a room temp. By this method, the metallic tin in the decopperized dross is selectively leached as SnCl2. Successively, the leaching solution and leaching slag are separated by filtration, etc. Thereafter, the aluminum pieces are dipped into the leaching solution and the metallic tin is precipitated and recovered as crude tin. On the other hand, in the leaching slag, copper is concentrated and used as raw material in a copper refining. Further, in the condition of incorporating scrap containing the aluminum in a flexible bag 2 having water permeability composed of acid resistance synthetic resin fiber, etc., this is dipped and washed in a cementation tank 1, water washing tank 5 and compressive squeezing machine 6 successively through a beam 3 and a lifting machine 4, and after removing the water, by carrying out by a container 7, recovery of the tin and the aluminum scrap can be efficiently treated.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a copper-removal dross treatment method. More specifically, the present invention relates to a copper-free dross treatment method for treating copper-free dross mainly composed of metallic tin and copper sulfide generated during a tin refining process and recovering tin. [0002] Decoppered dross is produced during the tin refining process when copper contained in crude tin is removed as copper sulfide by adding sulfur. When copper is removed, a large amount of tin is mixed into the decoppered dross. R. A. Written by WRIGHT, “
Extractive Metalurgyof
Tin”, 2nd Ed. , ELSEVIER Publishers, 1982, p. 226, describes the post-treatment of decoppered dross by oxidative burning. [0003] However, in recent years, the availability of high-quality tin raw materials has decreased, and the use of poor-quality tin raw materials has increased from the viewpoint of effective resource utilization, and as a result, the amount of decoppered dross generated has increased. Due to the increasing number of people, it has become necessary to utilize them effectively. Post-processing of decoppered dross is difficult, and the oxidation roasting method has a strong tendency to generate and sinter a copper-tin alloy during roasting.
It was difficult to perform roasting, which is an easy post-processing process, and was not an appropriate processing method. There was no other suitable treatment method and it was not used effectively. On the other hand, there is an increasing amount of scrap containing a large amount of aluminum pieces in recovered tin raw materials, and it is required to easily process this together with copper-removed dross. SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a method for easily recovering tin by processing dross, and also for processing scrap containing aluminum pieces. [Means for Solving the Problems] In the present invention, decoppered dross containing metallic tin and copper sulfide as main components is treated with hydrochloric acid to selectively leach tin, and the leachate and leach slag are separated. After that, a copper-removal dross treatment method was constructed in which the aluminum pieces were immersed in the leachate to recover tin. At the same time, a series of steps of immersion in the leachate, subsequent washing with water, and dehydration are carried out while the scrap containing the aluminum piece is placed in a container having good water permeability and flexibility. A processing method was constructed. [Operation] When decoppered dross containing metallic tin and copper sulfide as main components is immersed in concentrated hydrochloric acid at room temperature, the metallic tin generates hydrogen and dissolves, and the decoppered dross becomes a slurry. When solid-liquid separation is performed by conventional methods such as filtration, tin is added to the leachate from the decoppered dross.
0% or more is eluted and becomes a tin chloride SnCl2 solution. When aluminum pieces are immersed in leachate, metallic tin is precipitated and used as crude tin. The scrap containing the aluminum pieces is then preferably subjected to a series of soaking, rinsing and dewatering steps while still in a container having good water permeability and flexibility. Incidentally, the leaching slag is concentrated in copper to more than 60% and contains only a few percent in tin, so it is used as a raw material for copper refining. [Embodiment] An embodiment of the present invention will be explained with reference to FIG. FIG. 1 is a diagram showing a series of processing equipment for decoppered dross. One ton of decoppered dross was poured into 2 m3 of concentrated hydrochloric acid in an acid-resistant tank at room temperature little by little without being pulverized with stirring. Add hydrogen while monitoring the generation of hydrogen to prevent the reaction from becoming too intense. At this time, hydrogen sulfide is generated along with hydrogen, so provide local exhaust ventilation and be careful not to let the hydrogen concentration reach an explosive concentration. It takes about 2 liters to put in the entire 1 ton.
It took a while to finish. After that, stirring was continued and immersion was continued for 10 hours. The decoppered dross became a slurry. The resulting slurry was filtered using a filter press, and the filtrate was separated from the leachate. The reason for using concentrated hydrochloric acid is as follows. Concentrated hydrochloric acid reacts with decoppered dross at room temperature without pretreatment such as crushing the decoppered dross, and according to the reaction formula below, tin becomes stannous ions and hydrogen is generated. Sn +2HCl ─→
The Sn2++2Cl- + H2 reaction is quite violent, but not so much that it cannot be controlled by adding the decoppered dross little by little. The leaching rate of metallic tin becomes 90% or more when concentrated hydrochloric acid is used in an equivalent amount of 2 to 2.5 times the amount of metallic tin. Leaching of copper sulfide is small. Moreover, the residue can be easily filtered. In contrast, dilute hydrochloric acid (2+1
), the reaction is mild, but the leaching rate of metallic tin remains at about 80%. Copper sulfide does not dissolve, so the leachate contains almost no copper. Therefore, the decoppered dross has good properties and is suitable for preventing copper from being contained in the leachate. According to comparative experiments, sulfuric acid does not react with decoppered dross unless heated, and the leaching rate of tin is low. Furthermore, nitric acid reacts excessively violently, making it extremely difficult to control the reaction. [0010] The filtrate was diluted with water to approximately double the volume to 4 m3. This filtrate is mainly an aqueous solution of tin chloride, SnCl2, and contains 112 g/l of Sn. This aqueous solution was placed in an acid-resistant cementation tank 1. 400 kg of scrap containing aluminum pieces is packed into a bag 2 made of acid-resistant synthetic fiber with a coarse weave through which liquid can pass freely, and the bag 2 is lowered by an elevator 4 that can be moved horizontally by a beam 3 into a cementation tank 1. It was put in and soaked. Scrap containing aluminum pieces contains approximately 10 percent tin and approximately 60 percent aluminum, of which approximately 50 percent is metallic aluminum. Tin ions were precipitated as metallic tin in bag 2 according to the reaction formula below. 3Sn2++6Cl- +2Al
─→ 3Sn+2Al3++6Cl− As the immersion continued, the tin ions in the cementation tank 1 gradually decreased, and after 3 days, it contained only 0.10 g/l of Sn, and the removal rate reached 99.9%. Also, the concentration of aluminum chloride rose to 210 g/l. After 3 days, the soaking was completed, and the bag 2 was lifted up from the cementation tank 1 by the elevator 4, moved horizontally by the beam 3, lowered by the elevator 4, and placed in the adjacent washing tank 5 for cleaning. After cleaning, the bag 2 is lifted up again from the cementation tank 1 by the elevator 4.
It was moved horizontally by a beam 3, lowered by an elevator 4, and placed on an adjacent compressing and squeezing machine 6, where the contents of the bag 2 were compressed while remaining in the bag 2 and squeezed for dehydration. After dewatering, the bag 2 was lifted up by an elevator 4, moved horizontally by a beam 3, lowered by an elevator 4, and transferred to an adjacent container 7. Container 7 was sent to the smelting plant. [0012] The scrap containing aluminum pieces is placed in the bag 2 and processed through a series of labor-saving steps such as soaking, washing, dehydration, and transporting the tin slag to the smelting factory. This is because it becomes Furthermore, since the precipitation of metallic tin using aluminum pieces is based on the difference in ionization tendency between tin and aluminum, no auxiliary materials are required.
The precipitated tin slag is sent as raw material to a smelting factory without any treatment. The contents of the bag were 484 kg of tin slag containing approximately 83% tin and a small amount of impurities in addition to water, and the recovery rate of tin in the dross was 92.6%. The obtained tin slag was sent to a smelting factory and fed into a swash plate furnace as a crude tin raw material. Since the tin slag has already been reduced to metal, no further electrolysis is required and no electrical energy is consumed. The liquid remaining in the cementation tank 1 became an AlCl3 solution and was effectively used as a coagulant in the waste liquid treatment process. The leaching slag was mainly composed of copper sulfide (Cu2S), and the copper was concentrated two to three times, and was sent to a copper smelting factory and used as a raw material for copper. Next, a list of analytical values for decoppered dross, tin slag and leaching slag (undried) is shown. Analysis value list Sn Cu
S Fe Pb As
Al (%) Decoppered dross 48
25 6 2.0
1.0 1.5
Leach slag 7 65
10 2.5 1.0
1.5 Aluminum-containing scrap 9.6 0.5 <0
．． 5 0.6 1.4 <0
．． 5 ~60 Tin slag 83
0.3 <0.5 0.2
<0.1 <0.1 0
[015] According to the present invention, decoppered dross was treated and copper was recovered together with tin. Scrap containing aluminum pieces was also easily processed.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a series of processing equipment for decoppered dross.

[Explanation of symbols]

Claims (2)

[Claims] [Claim 1] Copper-free dross containing metallic tin and copper sulfide as main components is treated with hydrochloric acid to selectively leach tin, and after separating the leachate and leach slag, aluminum pieces are immersed in the leachate. A copper-removal dross treatment method characterized by recovering tin. 2. A series of steps of immersion in the leachate and subsequent rinsing and dehydration are carried out while the scrap containing the aluminum pieces remains in a container having good water permeability and flexibility. The copper-removal dross treatment method according to claim 1.