JPH0353032A - Method for recovering samarium and cobalt from samarium-cobalt alloy scrap - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for separating and recovering S- and Co from Srs-Co alloy scranop generated during the production of samarium (SII1)-cobalt (co) sintered alloy magnets. Regarding.

[Prior art] Scraps such as cutting chips and defective products are generated in the manufacturing process of Ss-Co alloy sintered magnets, but these Sm-Co
As a method for separating and recovering SII and Co from alloy scrap, Sa+-Co alloy scrap is dissolved in oxalic acid such as hydrochloric acid, nitric acid, or sulfuric acid, and oxalic acid is added to dissolve SII.
After II1 was separated by filtration as samarium oxalate precipitate,
Co was recovered as cobalt carbonate by adding carbonate to the oral fluid. However, with this method, it was difficult to completely separate Sm and Co. That is, in order to completely separate S1, a large amount of oxalic acid must be added, and at this time, Co also forms oxalate and co-precipitates with the oxalate of SII1, so it is necessary to add highly pure Sm. It cannot be recovered.

[Problems to be Solved by the Invention] Therefore, the purpose of the present invention is to solve the above-mentioned problems and to obtain a Sm-
An object of the present invention is to provide a method for recovering Sm and COO from Go alloy scrap.

[A thousand steps to solve the problem] In order to achieve the above object, the method of the present invention
o Alloy scrap is dissolved in sulfuric acid to make a sulfuric acid aqueous solution, and oxalic acid is added in an amount less than approximately equivalent to Sm in the sulfuric acid aqueous solution, leaving a small amount of Ss ions in the sulfuric acid aqueous solution, and precipitated samarium oxalate is filtered through the mouth. After separation and recovery, an alkali and/or carbonate compound is added to the oral filtrate to separate the precipitated carbonates of Sm and Co in the form of a hydrous precipitate, and the hydrous precipitate is treated with sulfuric acid to improve the quality of life. It is characterized by the fact that the aqueous cobalt sulfate solution obtained is separated and recovered from the undissolved samarium double salt.

[Operation] Figure 1 shows the procedure of the method of the present invention. Strr-Co alloy scrap that can be applied to the method of the present invention includes cutting waste generated during manufacturing Ss-Co alloy sintered magnets, cracked defective products, etc., and is not particularly limited. Rare earth elements such as lanthanum (La), cerium (Ce), and praseodymium (Pr), as well as iron (Fe) and nickel (Ni) may be included as impurities. When dissolving the Ss-Co alloy scrap in sulfuric acid, the sulfuric acid concentration is not particularly limited as long as the Sm-Co alloy scrap can be dissolved. If necessary, undissolved residue can be separated by filtration.

Although it is necessary to add approximately an equivalent amount or less of oxalic acid to S- in the sulfuric acid aqueous solution, it is important to leave a small amount of S- in the ion state in the sulfuric acid aqueous solution. If oxalic acid is added in excess of an amount equivalent to S in the sulfuric acid aqueous solution, not only will the entire amount of S be precipitated as samarium oxalate, but also co will be eutectoid as cobalt oxalate, reducing the purity of samarium oxalate. This is inconvenient. After the precipitated samarium oxalate is separated and recovered by filtration, an alkali and/or carbonate compound is added to the filtrate, but the alkali is not particularly limited.
Examples of the carbonate compound include sodium hydroxide, potassium hydroxide, etc., and examples of the carbonate compound include sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, ammonium carbonate, etc. Alternatively, they may be used in combination. The alkali and the carbonate compound can be used in the form of an aqueous solution or a powder. By adding the alkali and/or the carbonate compound to the oral fluid, the sulfuric acid aqueous solution is neutralized and the sodium sulfate is eliminated, but the alkali and the carbonate compound can be used at the same time or separately. It's okay to do that. When separating the SL1 and Co carbonate precipitates from the mouth filtrate, it is necessary to separate them in a water-containing state. Any conventional method may be used to separate the water-containing precipitate, but a filter press method is particularly suitable.

The water-containing precipitate may be in a solid or slurry state, but the important thing is that the water-containing precipitate must not be washed with water to remove the water in the water-containing precipitate and the sodium sulfate dissolved in the water. First, it is preferable that the water content is about 70% by weight. When treating the water-containing precipitate with sulfuric acid, it is necessary to dissolve only the Co precipitate in the water-containing precipitate, and it is preferable to dissolve Co so that it is 50 g/1 or more, and the sulfuric acid concentration used is 70 g/1 or more. % by weight is preferred.

In the above sulfuric acid treatment, the SI1 precipitate in the water-containing precipitate changes into sulfate and at the same time immediately combines with the sodium sulfate in the water-containing precipitate (SIlt(SO*)i' NazSo4
'811zO) forms an insoluble double salt and becomes a precipitate. Therefore, the insoluble Sll double salt can be thoroughly separated from the cobalt sulfate aqueous solution obtained by treating the water-containing precipitate with sulfuric acid, and cobalt sulfate containing no S1 can be recovered. [Example] Wet-pulverized Ss-Co whose analytical values are shown in Table 1
Alloy Scrap 40kg to 80 g/l HzSOn
Add 700 liters and melt by heating while blowing steam.
60 Il of sulfuric acid aqueous solution was obtained. Pr, Nd, and Ce contained in the scrap are rare earth elements like S+m and have high reactivity to oxalic acid. Oxalic acid was added, and oxalate was precipitated and separated by filtration.

The concentration of Ss in the furnace liquid was 1.2 2 g/l, and the concentration of Co was 22 g/l. Caustic soda was added to this mouth liquid to adjust the pH to 4.0, then 20 kg of sodium carbonate was added, and further caustic soda was added to adjust the pH to 10 or more.

When the resulting precipitate was filtered through a filter press, 6
A precipitate with a water content of 7% by weight was obtained. The si concentration in the oral fluid was less than 0.01 g/l. The above water-containing precipitate was dissolved in a tank by adding 70% by weight sulfuric acid 501 and water.

When this sulfuric acid aqueous solution was passed through a Denver filter, a cobalt sulfate (Co64 g/1) aqueous solution 2601 and a separated samarium sulfate/sodium sulfate double salt (dry weight 5.
9 kg) were collected.

Ss in cobalt sulfate aqueous solution is 0.16g/i! Met.

Table 1 As a result of the above treatment, the amount of SIl1 present in the cobalt sulfate aqueous solution was only about 0.6% by weight compared to the amount present in the scrubber, which was extremely low.

[Effects of the Invention] By carrying out the method of the present invention, Sa+ can be recovered from SLII-Co alloy scrap with simple processing and high recovery rate.
It is possible to separate and recover Co and Co, respectively, and the effect is great.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the procedure of the method of the present invention. Patent issuer: Sumitomo Metal Mining Co., Ltd.

Claims (1)

[Claims] Samarium-cobalt alloy scrap is dissolved in sulfuric acid to make a sulfuric acid aqueous solution, and oxalic acid is added in an amount less than approximately equivalent to the samarium in the sulfuric acid aqueous solution, leaving a small amount of samarium ions in the sulfuric acid aqueous solution and precipitated samarium oxalate. After filtration separation and recovery, add an alkali and/or carbonate compound to the filtrate to separate precipitated samarium and cobalt carbonates in the form of a hydrous precipitate, and treat the hydrous precipitate with sulfuric acid, 1. A method for recovering samarium and cobalt from samarium-cobalt alloy scrap, which comprises recovering the generated cobalt sulfate aqueous solution from undissolved samarium double salt by filtration separation.