JP5163988B2 - Electrolysis method of lead - Google Patents

Description

The present invention relates to a method for recovering Pb contained in non-ferrous smelting, a melting furnace for recycling raw materials such as bases and electronic components, and dry smoke ash generated from a dry furnace for melting industrial waste.

In order to recover Pb contained in non-ferrous smelting dry ash from non-ferrous smelting, melting furnaces for recycling raw materials such as foundations and electronic parts, and dry furnaces for melting industrial waste, fumes are leached with sulfuric acid, After changing to lead sulfate, smelting reduction is performed in an electric furnace. The metal separated by smelting is treated with soda, and then the metal is anode cast, and then Pb is recovered by electrolytic purification in a silicofluoric acid bath.
With respect to Patent Document 1, high purity electrodeposited lead is recovered by a sulfamic acid bath for a high Bi grade anode.

In Patent Document 1, the optimum current density is 50 A / m 2 or less. However, in order to increase the amount of lead recovered, the initial cost increases, for example, by increasing the number of battery tanks. Therefore, it is desirable to further increase the optimum current density.
Reference number T21-0202 Electrolysis method of lead Patent applicant :: Nikko Metal Co., Ltd.

It is an object of the present invention to provide a lead electrolysis method capable of recovering high-purity lead even for a high-Bi grade anode with respect to the prior art.

The present inventors made the following invention in order to solve the above-mentioned problems.
(1) In electrolytic refining in a sulfamic acid bath using a high impurity anode of Bi grade 5 to 30 mass%,
After performing electrolysis for 2 hours or more at a current density of the first stage of 50A / m2
The lead electrolysis method recovers high purity lead by electrolysis at 100 A / m2 or less as the second step.

According to the present invention, a lead electrolysis method characterized in that high-purity lead with extremely low Bi quality can be recovered efficiently from a high Bi quality lead anode without further capital investment.

The present invention is described in further detail below.
The raw material contains 70 to 90 mass% lead, 0.04 mass% tin, and 5 to 30 mass% bismuth in the lead-containing material of the present invention. This is because when bismuth is increased to 5 to 30 mass% in the anode, the contamination of bismuth in the electrodeposited electrode lead increases.

For example, the lead-containing material is subjected to anode casting, and electrolytic purification is performed using the anode. By making the anode size smaller than the cathode size, the edge effect can be prevented, and smooth and good electrodeposited lead can be recovered.

As an electrolytic solution, the concentration of sulfamic acid is optimally 20 to 100 g / L, and the lead concentration is optimally 40 to 80 g / L. Furthermore, smooth and good electrodeposited lead can be recovered by setting Neugen BN-1390 or Neugen BN-2560 to 1 to 10 mg / L as the smoothing agent.

Next, as the energization method, the first stage energization was conducted for 2 hours or more at a current density of 50 A / m ² or less, and then the second stage was conducted at a current density of 100 A / m 2 or less. As described above, low-Bi-grade electrodeposited lead having a Bi grade of 5 ppm or less can be recovered as compared with electrodeposited lead energized at a current density of 100 A / m 2 in the initial stage.

(Example 1) Method of recovering low Bi grade electrodeposited lead As the composition of the electrolyte, 10 mg of Neugen BN-1390 as a smoothing agent was added to a solution adjusted to lead concentration: 80 g / L and sulfamic acid concentration: 20 g / L. Add to / L.
A high Bi grade lead anode and lead seed plate or stainless steel plate is used as a cathode, and the batteries are alternately inserted. It is optimal that the size of the cathode be about 20 to 30 mm larger than the anode because the current concentration on the edge portion can be relaxed.

After the electrode is charged, the electrolytic solution is replenished in the battery case, and the concentration distribution in the battery case is made uniform by supplying the electrolyte solution so that the residence time of the electrolytic solution in the battery case is about 1 hour.
After adjusting the electrolyte temperature to 20-30 ° C, the current density at the first stage was energized at 50A / m2, and after 2 hours the current was energized at 100A / m2 as the second stage. 5 massppm of low Bi grade electrodeposited lead could be recovered.

Relationship between energization method and Bi quality in electrodeposited lead, which is an embodiment of the present invention

Claims (1)

In electrolytic purification in sulfamic acid bath using high impurity anode of Bi grade 5 to 30 mass%,
After performing electrolysis for 2 hours or more at a current density of the first stage of 50A / m2
A lead electrolysis method characterized in that high purity lead can be recovered by electrolysis at 100 A / m2 or less as the second step.