Separation of bronze and tin alloy hybrid chips

Huang Kaiguo Xu Wenxian

First, the choice of separation program

I tried using a difference between the two melting point alloy (ZQSn663 bronze mp 967 ℃; ZChSn 116 tin alloy melting point of 370 deg.] C) melt temperature separation, but never the molten tin alloy is difficult to melt the end of the chip surface is completely bronze Cleared, the separation did not give satisfactory results. It is also impossible to separate this complex and stable hybrid material directly into bronze and tin alloy for reuse by fire or hydrometallurgy. It can only be melted into a certain low-grade alloy, or some metal is extracted for use, and the process is complicated, the cost is high, and there is pollution of waste gas or waste water, which is not preferable.

According to the difference of physical and chemical properties of bronze and tin alloy scraps, the method of beneficiation is used to separate the original components, structures and properties of copper and tin scraps, respectively, and the briquettes and tin alloy scraps are obtained respectively. Further smelting, tuning, for bearing production, or casting into bronze ingots and tin alloy ingots is a simple and effective method. The end of the scrap iron mixed cuttings, magnetic separation can be used to clear. Flotation separates the fine copper ends from the tin, but the particle size of the mixed chips is -5 mm, far exceeding the effective particle size (-0.2 mm) of the flotation. Because this material has good ductility and cannot be finely ground. Further, the bronze is an alloy containing copper, tin, lead, zinc, tin alloys have buoyant copper, antimony, conventional flotation separation effect is very bad. Re-election can separate the two materials with large difference in specific gravity. However, in this mixed shoulder, the specific gravity of the bronze crumb is 7.46, and the specific gravity of the tin alloy crumb is 6.89. The difference between the two is small. Depreciation ratio In the formula For heavy material weight, For the light material specific gravity, â–³ is the specific gravity of the separation medium. then It is a re-election of two materials that are extremely difficult to separate. Moreover, the shape of the material is irregular and the separation is more difficult.

In this research, a new “grading-desktop flotation separation method” was successfully carried out. The principle flow is shown in the following figure. After the mixed materials are removed from iron, removed, sieved, water is added, and separating agent is added (F ₃ , F7). Etc.), on a special equipment, according to certain process conditions, you can separate the pure bronze scraps and pure tin alloy crumbs.

Second, the separation condition test

After the iron ends and impurities were removed, the sieves were divided into three grades of -5+3, -3+1, and -1mm, and conditions of nine process factors were tested. The conditional test represented by the 2-factor 2 level orthogonal design test with -3+1mm grain size is as follows:

The two factors are: A, separating agent F3, B, separating agent F7. They are used in two levels, 500, 700 and 100, 150 g / ton, respectively, listed in the 2 ² factorial test schedule, the results of the factorial test and its effects are shown in Table 2.

Table 1 2 ² factorial test arrangement

In Table 2, the test conditions of Pilot 1 are A500g/t and B100g/t; Pilot 2 is A500g/t, B150g/t; Pilot 3 and 4 are pushed. AB is an interaction. The test results of the pilot 1: the weight percentage (yield γ%) of the tin (a) obtained by the separation was 38.0%, and the test result contained 80.86% of Sn; the obtained copper (b) yield was 56.1%, and Cu was 86.06%. . Pilots 2, 3, and 4 are analogous. The effect γa ^A is the difference between the average yield of the peaks of the factors A and the high level (the amount) of the pilots 3 and 4 and the average yield of the low level pilots 1 and 2, ie

The same reason:

effect Is the difference between the average tin content (grade) of the peaks of the high-level pilots 3 and 4 of the factor A and the average tin content of the tin of the low-level pilots 1 and 2, ie

The same reason:

From the results of the factorial test and the effect calculation results in Table 2, it can be seen that:

(1) When the amount of A (separating agent F3) is increased, the yield of copper (b) is increased (+2.5), the effect is large, and the yield of tin (a) is correspondingly reduced, and the effect is -2.25.

(2) The amount of B (separating agent F7) increased, the effect on b was significant (+0.60), and the yield increased, but the effect on the yield of a was small, and the effect was +0.05.

(3) A and B have obvious yield interactions (ab) for a and b, a is negative (-0.65) and b is positive (+0.70).

(4) The increase in the amount of A and B is beneficial to the increase of the tin content in the tin, that is, the quality of the tin is improved. Their effects in the table are +1.10, +0.17. Their interaction (AB) is positive (+0.25), which promotes each other.

(5) The increase of A dosage is beneficial to the increase of copper content in copper powder. The effect is positive (+0.44), but the increase of B dosage is not conducive to the improvement of copper quality, and the effect is negative (-0.84). The interaction between A and B on copper ends is reversed (-0.12).

Obviously, the pilot 3, A high level (F3 is 700g / t), B low level (F7 is 100g / t), the test results are the best, bronze scraps contain 86.38% of copper, tin alloy scraps contain tin 82.21% .

In order to further improve the quality of tin alloy crumbs, on the basis of maintaining A of 700g / t, when the amount of B is increased to 200g / t, the quality of the tin alloy crumbs is obtained, containing 82.40% of the yield. It is 39.3%. At this time, however, the quality of the bronze chips was reduced, containing 84.46% of Cu, and the yield was 56.5%.

The effects of the above two factors (separating agents F3 and F7) in the factorial test reflect the performance of the two agents.

Similarly, the other seven factors are tested by one-factor test or multi-factor combination test to find the best process conditions. The optimum separation process conditions for each particle size are shown in Table 3. It can be seen from the table that as the particle size of the mixed chips increases, the amount of the separating agent and the amount of water also increase accordingly. For the mixed chips larger than 1mm, high-quality bronze chips can be obtained after one rough separation; and the mixed chips less than 1mm need to be re-selected to obtain better quality bronze chips. The tin alloy crumbs of each grade need to be selected 2 to 3 times to obtain better quality, and often mixed with sand. However, these sands can float on the surface when smelting at the end of the tin powder, which is useful for heat preservation.

Table 3 Optimal separation conditions

Third, the separation test results

The small test results of the mixed ends of each fraction at the optimum separation conditions are shown in Table 4. Obviously, each particle size can achieve good separation. Among them, the separation of -3+1mm grain size: the results of multi-element test of bronze chip and tin alloy chip, respectively, are shown in Table 5. This is very close to the standard ZQSn663 bronze and ZChSnSb116 tin alloy content, through melting, component optimization, can fully meet the standard.

This separation process was first industrially tested and succeeded in one fell swoop to achieve satisfactory results. Industrial test indicators are shown in Table 6.

Table 4 Separation results of each fraction of mixed fractions

Table 5 -3+1mm fraction separation products and standard bronze and tin alloy content (%)

Table 6 Industrial test results of separation of various grades of mixed chips

Fourth, the benefit comparison

The technical process of the technology is simple, the implementation is easy, the separation effect is good, and the economic benefit is high. The existing separation equipment (1 million yuan / Taiwan), the annual production capacity of 20 tons, each separation of one ton of copper, tin mixed scraps only need to consume 200 degrees, water 100m ³ , 0.7kg of separation agent. Low production costs, including separation and smelting adjustment costs, less than 0.1 million yuan per ton. Less people are required, 2 people per class. If the ratio of bronze scraps to tin alloy scraps in the original scrap is 3:2, the two products obtained by separating one ton of mixed scraps are separately smelted, tuned, and sold after ingot casting, which can add 1 to 20,000 yuan/ton. . The greater the proportion of tin alloy in the original waste, the greater the yield of the tin alloy obtained by the separation, and the higher the economic value. If the scale of production of mixed debris separation is expanded and used directly in the production of bearing bushes, the economic benefits are considerable. Compared with the development of underground resources (mining), processing and smelting of metals, this shows the superiority of developing and utilizing renewable resources. It is understood that the construction of a mining-selection-smelting small joint enterprise that produces 200 tons of metal copper and tin annually requires at least more than 20 million yuan of investment and 3 to 5 years of construction. The establishment of such a small plant that uses the "waste"-metal mixture to produce 200 tons of metal, as long as the investment of more than 100,000 yuan, construction for 3 to 5 months, can be put into production. Obviously, the development and utilization of renewable resources have the advantages of low investment, short cycle and quick effect, which are of great practical significance.

According to domestic investigations, international online search, this technique of separating bronze and tin alloy hybrid chips has no precedent at home and abroad, and is a very successful and significant advanced technology. Has applied for a Chinese patent.

V. Conclusion

(1) Bench-top flotation is an extremely simple and effective method to achieve the separation of bronze and tin alloy hybrid chips. It can completely separate the hybrid chips with a particle size of less than 5mm into two products, namely bronze chip and tin alloy chip, which meet the requirements of the content of each element of standard bronze and tin alloy. There is no precedent at home and abroad.

(2) The ends of the mixed chips need to be separated by sieving and separated under different optimal process regulations to obtain the best results.

(3) Separating agents F3 and F7 are a pair of key factors, and the two are used reasonably and properly, and the effect is best.

(4) The process flow is simple, the implementation is easy, the investment is small, the cost is low, the separation effect is good, and the economic benefit is large.

(5) This technology is the separation of the mixed scraps of bronze and tin alloys, which opens up new avenues for the development and utilization of metal renewable resources and has broad application prospects.

The Chinese version of this article was published in the "National National Mineral Processing Association" in October 1991. The proceedings of the conference were P.316-321.

The English version was published in 1993, "Korea EARTH 93' East Asian Renewable Resources Utilization Academic Conference", conference proceedings P.422 ~ 429 ☺

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