JPS6150127B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for reusing casting waste, cutting waste, and maraging steel scrap generated during the processing of maraging steel as raw materials for maraging steel melting. Conventionally, when iron-based metal scraps are recycled, they are melted in an electric furnace and refined by a reaction between the molten metal and slag, or by oxygen blowing, powder blowing, or the like. The so-called "dry method" is generally used, and maraging steel is no exception. However, when this dry method is used to regenerate maraging steel, there are the following problems. 1 In atmospheric dissolution and oxygen blowing, which are dry scouring processes, A contained as a component of recycled materials
, Ti oxidizes and becomes fine inclusions that are dispersed in the recycled material, but in materials that are characterized by their ability to withstand high stress, such as maraging steel, minute inclusions can also cause abnormal fractures. The presence of inclusions is undesirable because the 2 To avoid oxidation of A, Ti, vacuum melting is used, but maraging steel scraps
It has a strong spring-back property, and even if a large volume of scrap is melted, the amount of bullion collected is small, so when processing a large amount, the number of batches increases and vacuum breaking and suction must be repeated. , it is uneconomical. Furthermore, in vacuum melting, it is difficult to remove S contamination, which hinders the recycling of recycled materials. 3. Since the removal of impurities must be carried out in a molten state, the method is naturally limited. On the other hand, maraging steel scraps are dissolved in acid and this acid solution is electrolyzed.
If the treatment is carried out by the "wet method", these difficulties in the dry method are completely removed, but by simple treatment with an acid solution, it is impossible to deposit the metal at the cathode and recover it. It turns out it's possible. The present invention eliminates the above-mentioned drawbacks of the prior art, and provides a maraging method that can provide a high-purity alloy equivalent to electrolytic metal at a low cost as a raw material for maraging steel, which requires a high level of quality. The purpose is to find a way to reuse steel scrap. In the present invention, in order to achieve this objective, maraging steel scraps are dissolved in hydrochloric acid or sulfuric acid to create a liquid containing Fe, Ni, and Co, and the Mo concentration in this liquid is adjusted to be 15 mg/ or less. After Mo is removed, this liquid is electrolyzed to recover Fe, Ni, and Co as a high-purity alloy for use as raw materials for melting. Hereinafter, the present invention will be explained in detail based on examples thereof. Maraging steel is made of Fe, Ni, Co, Mo, Ti, etc., and when melted with dilute sulfuric acid or dilute hydrochloric acid, the melting continues until the pH at room temperature reaches around 1.5 to 3.5. In this case, Ti undergoes hydrolysis after elution.
Ti precipitates as O ₂ , and Mo also precipitates as a lower oxide, but almost all of Ti precipitates, whereas
Approximately 20 to 1200 ppm of Mo remains in the liquid depending on the conditions. The present inventors electrolyzed this solution to produce Fe, Ni, Co
An attempt was made to recover Fe, Ni, and Co as an alloy, but a black precipitate adhered to the surface of the cathode. I confirmed that it cannot be affected. Therefore, the present inventors further investigated the cause of interference with metal deposition by electrolysis, and found that
We found that the cause was related to the Mo concentration in the liquid. That is, from the acid solution of maraging steel
When Mo was removed step by step and electrolysis was performed,
The results shown in the table were obtained.

[Table] From this table, the Mo concentration in the electrolyte is 0 to 6 mg/
In the range of , the precipitated metals are Fe, Ni,
It is collected as an alloy of Co, but if it is 6 to 15 mg/mo, it is recovered as a slightly brittle metal with molybdenum oxide added to it, and these can be used as raw materials for melting.
It can be seen that when the concentration is 15 mg/min or more, Mo oxide only precipitates and the metal cannot be recovered. In addition, the molybdenum concentration is also related to the current efficiency of metal recovery; when the Mo concentration in the electrolyte is 3 mg/, the current efficiency for the precipitated alloy is 87%, but 12
At mg/, it is 75%, and at 15 mg/, it is estimated to be around 70%, so from this point of view, 15 mg/ is considered to be the limit of Mo concentration. On the other hand, usually in alloys containing Fe, Ni, and Co, Fe
〓 is oxidized to become Fe〓, which is precipitated and removed, and then Ni and Co are recovered. This precipitate of Fe is used as red iron material, but even after undergoing processes such as filtration, washing, drying, and calcination to recover it, red iron material is only valued at about 300,000 yen per ton. , 10-20% Ni with precipitation,
Co precipitates and is lost. In contrast, in the present invention, Fe is recovered by alloy electrolysis, thereby reducing the cost of producing Fe precipitate into red iron and Ni, Co
This eliminates the loss of steel and replaces it with electrolytic iron, which is blended during the production of maraging steel. The price of electrolytic iron is approximately 500,000 yen per ton, but the required power is 1200KW, so the electricity price is 20%.
Even in terms of yen/KW, it costs only 24,000 yen, which shows that it is much more advantageous than red iron manufacturing. As mentioned earlier, the conventional recycling of maraging steel is by the dry method, but this dry method has the serious drawback that it is difficult to completely remove inclusions. In the wet method, this drawback is completely removed and high-purity metals can be obtained, but by simple treatment of the acid solution, it is impossible to deposit and recover the metals on the cathode by electrolysis. However, in the present invention, the reason why metal precipitation cannot be recovered by this wet method is due to the presence of metal in the components.
Find out that it is due to Mo, find its limit amount,
This alloy was successfully recovered as Fe, Ni, and Co alloys through electrolysis, and as a result, it was possible to produce a low-sulfur smelting raw material containing almost no inclusions from maraging steel scraps, which could not be done using conventional methods. Furthermore, when the raw materials are dissolved with hydrochloric acid, it exhibits the excellent effect of obtaining recovered metal with extremely low sulfur through simple liquid treatment.

Claims (1)

[Claims] 1. Dissolve maraging steel scraps in hydrochloric acid or sulfuric acid to create a solution containing Fe, Ni, and Co, remove Mo from this solution so that the concentration of Mo in the solution is 15 mg/l or less, and then, This solution is electrolyzed with Fe,
A method for reusing maraging steel scraps, which is characterized by recovering Ni and Co as high-purity alloys for use as raw materials for smelting.