RU1277492C - Method of producing powder from slime waste of steel - Google Patents

Abstract

METHOD FOR PRODUCING POWDER FROM SLUDGE WASTE OF STEELS, including mechanical separation of lubricating coolant, heat treatment of a mixture in a reducing gas atmosphere, sieving and cenapaiyiio, which means that in order to improve the quality of the powder, heat treatment is carried out in miiXTbi at 500 deg; C for 20-40 minutes, and after separation, the powder is annealed in a reducing atmosphere at 600-750 C.

Description

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tWbxSia The invention relates to the field of powder metallurgy, in particular to methods for producing metal powders from uuiaMaj formed after grinding operations. The aim of the invention is to improve the quality of the powder. The method is carried out as follows. At the first stage, the cutting fluid is mechanically separated from the sludge, at the second stage, the mixture is heat treated in the atmosphere of undissociated ammonia, at 500-600 ° C for 20 AO min. In this case, embrittlement of the metal fraction occurs. The mixture, subjected to the indicated embrittlement annealing, is freely sieved on a vibrating screen with a mesh size of 50 microns or more without preliminary grinding. Such annealing eliminates the formation of cakes due to the low temperature. Elimination of the mechanical grinding operation eliminates the formation of a pentiform abrasive fraction. Sifting on a vibrating screen leads to the destruction of the chip form of susceptible to embrittlement of metal particles of sludge. Subsequent magnetic separation ensures a good separation of abrasive particles from the metal fraction of sludge waste. After magnetic separation, the powder is burned in a reducing atmosphere at 600–750 ° C. Example 1 i ShKh15SG sludge is mechanically removed from the grease-cooling fluid (centrifuged), annealed in ammonia atmosphere, sieved on a vibrating screen, with a mesh size 50 microns and subjected to double electromagnetic separation. Annealing temperature, annealing time AO min. . . The chemical composition of the obtained powder is given in table. 1. Example 2. Annealing temperature of 600 ° C, annealing time of 20 minutes The chemical composition of the semi-black powder is given in table. 2.

Example 3, Annealing temperature, annealing time of 30 minutes

The chemical composition of the obtained powder is given in table. 3.

The choice of the indicated temperature range (500-600С) is due to the following circumstances

sensing bodies), the formation of submicron dust-like particles of abrasive, reducing the quality of semi-black powder, is prevented (wear of molds of 55 forms increases, mechanical properties of sintered products decrease);

- preliminary brittleness of the charge by annealing in the atmosphere, non-dissociation, heat treatment at T 500С does not lead to embrittlement of the metal fraction, as evidenced by the results of sifting the resulting mixture on a sieve with a mesh size of 50-200 μm, heat treatment, at T 600С leads to structural annealing of the material of the metal fraction and a significant change in the magnetic characteristics, which in turn cause an increase in the fraction of the nonmagnetic fraction separated during separation, 4-6 shows the parameters of the proposed method. Effect of temperature of embrittlement annealing of sludge on magnetic separation and sifting of the obtained powder of steel ШХ15 (t., 30 min). The selected time interval (2040 min) is due to the following circumstances: annealing at min leads to very poor sifting quality of the charge, annealing at min leads to excessive nitriding, to an increase in the percentage of non-magnetic fraction during separation. Effect of time of embrittlement annealing of sludge on the magnetic fraction and sifting of the obtained powder of steel ШХ15 (T. 650С). . As can be seen from the table. 5, at t 50 min, the amount of non-magnetic fraction (t1-15%) extracted as a result of magnetic separation exceeds the amount of abrasive in the sludge (8-10%). The effect of reducing annealings in a hydrogen atmosphere on the compressibility of powders and impurity content (N., 0) (annealing time 1.5 h). Thus, the proposed method allows to improve the quality of the powder, because: after embrittlement annealing, the spiral structure of the particles of the metal fraction of the grinding sludge is easily destroyed, which contributes to the release of abrasive particles during subsequent separation. Since grinding of embrittled metal particles occurs during sieving without shock (no grinding Powder

  0.4-0.02 0.027 0.95 From sludge steel ШХ15СГ t, 0 Temperature

Not screenable

- ;; 0:,:, .//-.

:. -0.;, /:.::. ,:. 0: -,.,:;:.;. ;; 27-35

Shaving screening

  ABOUT ,, ; :Ltd

T a b ji i c a 3 0.72

Table 4

6-8

6-8

7-8

27-35

Table 5

Not separated because it did not succumb to screening

 -; -, 5-7-. . ;;. , - 6-8,. .

.-- /. 11-15 Content of components,% I ± IHZ i-iZE lI5ir: 11. . Residue on the sieve 20 d μmj The amount of non-annealing after sieving, Z I magnetic fraction, Z 0.02 0.02 1.23

h 3 .12774924

ammonia allows providing. It is possible to yield a suitable powder by comparing the structure of particles to a metal nanosecond with electromagnetic separation of the fraction after the sieving process, of equiaxed particles, which are once the most optimal for the subsequent sintering after high-temperature electromagnetic separation. Varietal j annealing according to the prototype method; Wearing the transverse sizes of the dipole particles to the longitudinal sizes (1: 5– - carrying out the subsequent restoration of 1: 10) ensures effective separation annealing improves the compression of the magnetic (metal) and powder without being washed and reduces the content of magnetic (abrasive) fractions and increased oxygen. / Powder I - 1- | С Cr From steel ШХ15СГ (standard) 0.95- 1.31, 1 1.65 From steel slurry, ЩХ15СГ; 0.95- 1.31, 1 1.4. Powder L.l..L

From ST9LI

SHH15SG

(standard) 0.950, 91, 31, 2 1.1 1.65

From sludge steel ШХ15СГ 0,85

1.21 0.9

0.40, 02 0.027 0.65

0.6 0.02 0.02 0.3 1.65 Component content,% -j-j --- Mn Si S P I 0, .Nj 0.9-0.4 - 0.02 0.027 1.2 0.65. 0.9- 0.4- 0.02 0.02 0.52 0.7 1.2 0.65 Content of components,% --1-- | -1 --- j r- :: --- l - - .-- Li, -LL - L ± -.Li --- -. Table Tables 2

The impurity content in the recovered powder, wt.%

0 „

Source powder without

restorative

atmospheric annealing

hydrogen

500

600

 700

750

850

Table b

FFpeccyeMOCTb powder after reconstitution annealing

.1...

, 63

Unsatisfactory same

Good Excellent Same Education Spec