Mineralization and mixing
The mass distribution of ore in any mine within the scope of a full deposit is always uneven. In order to ensure normal production and beneficiation plant, good technical and economic indicators, selected ore requirements of quality indicators must be balanced and stable. To this end, in general, the ore is blended and mixed. The method is to build a blending and mixing yard, or to use a simple blending and mixing facility. When the ore blending and mixing yard is used, the ore blending and mixing are carried out in the stockyard; when using the simple blending and mixing facility, the ore blending is usually in the mining yard, on the rough front bridge or in the concentrate bin. Carry out; mixing is carried out during crushing, screening and transportation.
(1) Mineralization and mixing in various situations 1. Mineralization and mixing in the mine face According to the requirements of the ore quality index of the ore dressing plant, according to the mine geological data, combined with the actual mining design. According to the design, the mining section is selected reasonably, the number of mining heads, the order and proportion of mining are considered, and the factors such as the surrounding rock are mixed. The different quality ores produced are loaded according to the design requirements of the ore, and the ore is determined according to the determined formation plan. It is sent to the coarse crushing trestle of the concentrator. According to the basic characteristics of the ore and the optional test results, the method of blending and mixing the car is carried out, and then it is crushed, sieved, stored, unloaded and transported. The ore is further mixed to meet the quality requirements of the ore selected in a certain period.
2. Distribution and mixing in the ore dressing yard of the ore dressing plant Some ore dressing plants have more types of ore (or purchased ore) from different mines, and the quality indicators are different. The ore is transported separately to the ore dressing plant after the ore dressing yard. According to the basic characteristics of various ores and optional test results, some ore will be selected within a certain period, and will be selected after the expiration, so that the ore quality after ore blending is balanced and stable, meeting the process requirements of the concentrator.
Another commonly used method of ore blending is the layering method. This method is to pile up the transported ore in the ore yard with a number of layers that are parallel to each other and overlap each other as required. The weight of the layers is substantially equal, and the number of layers per pile can be several hundred layers, and the layered paving itself is the ore. After the pile is formed, all the layers are cut from the pile perpendicular to the entire section of the layer by a reclaimer, which is an effective mixing method. Some stockyards use electric shovel for ore blending and mixing.
3. Mineralization and mixing before ore dressing after grinding. This method is to store the ore from the mine separately according to the quality, crush and grind separately, and then send them to the mixing tank for mixing and mixing according to requirements. The evenly distributed slurry is sent to the next operation. SKS lead ore and zinc ore purchased the mineral ore production in proportion to the respective predetermined crushing and grinding, after passing the required size are sent to the same tank for stirring and mixing ore, and then to the flotation .
4. Mineralization and mixing in the concentrate yard <br> Concentrate ore is to classify and concentrate the different grades of concentrates according to different requirements of smelting, and then leave them as commercial concentrates. Concentrate ore blending can be dumped in a concentrate warehouse with a grab crane or separate grades of concentrate in a silo, and then discharged and loaded from the silo as required.
5. Mixing in the silo <br>The ore is mixed to a certain extent through the process of crushing, sieving and transporting, especially the ore in the intermediate storage silo and the grinding silo by moving the unloading truck or shuttle belt The layered fabric is woven back and forth, and the discharge device at the bottom of the silo is discharged as planned to further mix the ore. This mixing method has been applied in the production of many concentrators in China. The ore dressing workshop of Donganshan Sintering Plant of Anshan Iron and Steel Co., Ltd. has certain effect by mixing this ore with this method, as shown in Table 1.
Sampling location | Number of samples (n) | Standard deviation (S) |
Before mixing, in the face of the mine | 313 | 1.48 |
Primary classifier overflow after mixing | 329 | 1.11 |
Note: The data in the table is the production statistics for October 1984. [next]
(2) Calculation of mixing effect The calculation of the mixing effect is generally expressed by the ratio of the standard deviation of the feed components to the standard deviation of the discharge components. The standard deviation is calculated as follows: (1-1):
   Where η - mixing effect;
S E - standard deviation of feed ingredients;
S A - the standard deviation of the discharge composition.
If the value of η in the formula (1-2) is larger, the better the mixing effect is. In practical applications, in addition to using the η value to reflect the mixing effect, the standard deviation of the discharge component can also be used to indicate the mixing effect, because this representation is more intuitive to use. China Shiling Cement Plant has conducted several mixed industrial tests on limestone from April 1979 to October 1982. The results are shown in Table 2.
Test number | Feed standard deviation | Discharge standard deviation | η |
GS-I | 93.44±8.8 | 94.08±1.6 | 5.5 |
GS-II | 94.72±5.65 | 95.43±0.89 | 6.4 |
GS-III | 93.97±6.72 | 94.31±0.86 | 7.8 |
GS-IV | 91.75±6.64 | 91.77±1.02 | 6.5 |
It can be seen from the data in Table 2 that the third group has a large η value and a small standard deviation of discharge, indicating that the mixing effect is good, the second group is second, and the first group is the worst.
In the ore blending and mixing design, it is often necessary to calculate the mixing effect after setting the ore blending and mixing process under the known raw material conditions. In this case, the following empirical formula can be used:
Where s Q is the predicted value of the standard deviation of the material on the take-up section;
s E - the standard deviation of the feed ingredients;
n - the number of layers of material piles.
The calculation results with this formula must be corrected according to the different types of reclaimers.
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