Trial-manufacture and application of as-cast low chrome alloy casting grinding media balls (3)
2.The actual production process of casting grinding media ball and its performance testing results
2.1 Production process
According to the designed composition, the molten iron is smelted by induction furnace; after slag removal, temperature adjustment, alloy addition, sampling analysis, and adjusting the composition to be qualified, the molten iron is drawn out at 1500 ~ 1550 °C and is modified by the inner-ladle method, at 1400 ~ 1450 °C, Molten iron is poured to form a casting grinding media ball. The Chemistry and composition of Fsq direct-reading spectrometer produced by John Logie Baird, USA, were tested.
2.2Performance test results
2.2.1 Mechanical property
The test results of hardness and impact toughness of casting grinding media ball (20mm ×20mm, complete oral sample) are shown in Table 1
2.2.2 Falling times of the casting grinding media balls
The MODEL MQ2 III ball falling machine simulates the actual working condition of the ball casting and raises the ball continuously to 3. 5 M above a fixed height, free-fall, impact with constant impact energy. It is one of the effective means to determine the impact fatigue life of cast balls when they fail.
According to the requirements of YB/T09221996, a batch of 100mm standard balls were poured into the molten iron of 5 # sample in Table 1. The results are as follows in Table 2.
It can be seen that this index has greatly exceeded the standard value of 8000 life cycles stipulated in YB/ T092-1996.
3.Using result in the industry
3.1Industrial test results of typical casting grinding media balls
In the process of trial production, it is found that the large diameter cast ball is more difficult to be trial-produced. Under the same working condition, the large diameter cast ball is more easily broken and worn. In order to explain this problem, this paper presents the industrial test of a 125mm diameter cast ball.
Trial Unit: No. 1 Ball Mill in Section 1, Daye iron ore dressing plant, Wisco.
TEST RUN TIME: June 28 ~ July 24, 1997, run 528. 8h, the operating rate is 86%.
Trial Total Pitch 59. 96 T, mill memory ball 42. 205 T, actual consumption ball 17. 755t.
Handle mixed ore volume 34276. 82 T, average station time 64. 82t.
Average ball consumption: 0.518 kg/t raw ore.
Broken Rate: After the test stop, open the bin into the ball mill to count and measure the surface crushing ball, found in 3000mm × 3100mm area, only four crushed balls, the actual crushing ball rate is far less than 1%.
3.2 Statistical results of industrial use
In 1998, the total ball use and the total grinding amount were counted, and the results were shown in Table 3.
3.3Economic benefits comparison
Taking the 125mm diameter grinding balls used in the first stage grinding ball mill of the concentrator of Daye Iron Mine of Wisco as an example, the economic benefits are compared as shown in Table 4.
4.Conclusion
It has been proved in production practice for several years that the series of as-cast low chromium alloy cast balls can be used normally in the large and medium-sized ball mills under 3200mm in iron ore, copper ore and phosphate ore, and the economic benefit is obvious. But in the production of casting ball, we must grasp the following points: (1) strictly control the chemical composition and range, different specifications, casting ball its control focus is not the same. (2) reasonable design of the gating system, strict control of Molten iron quality, to ensure that there is no hole defect inside the casting ball. (3) it is appropriate to use a reasonable structure of the metal mold to produce a cast ball to ensure that the solidification and solidification cooling rate are controlled in an appropriate range.
