Picking theory (4)

In a radio resonance method (conductance-magnetic method), a component (coil or capacitor) that generates an alternating electromagnetic field can simultaneously be a component that detects changes in an electromagnetic field; or two components, one for generating an electromagnetic field, The other is used to detect changes in the electromagnetic field.
Radio resonance method is suitable for a variety of non-ferrous metals, ferrous metals, rare metals and coal preparation. The sensitivity of the sorting method is also high, and good results are obtained when sorting heavy metal oxide ore and sulfide ore such as copper , nickel , lead , and zinc . [next]
III. Factors Affecting Picking Factors The main factors affecting the quality of picking are as follows:
(1) The distribution of the useful components in the nuggets is uneven, and the detected features do not reflect the actual conditions of the nuggets;
(2) The shape of the nugget is irregular. It is usually difficult to accurately determine the weight of the nugget by using the method of measuring the nugget size to estimate the weight of the nugget;
(3) The relationship between the sorting characteristics and the useful components in the nugget is not strictly positive correlation;
(4) The detection time is too short (several milliseconds, tens of milliseconds), and the sensitivity of the detector is not enough;
(5) The ore is not uniform. When the two ores overlap or are too close, the measurement results are disturbed; when the ore blocks deviate from the detection center, the measurement results are biased;
(6) The action of sorting actuators (such as electromagnetic jet valves) is not very accurate, affecting the rate of blowing.
Among the above various factors, several can be improved from improving the quality of the picker, but most of them are of a probabilistic nature, making the picking efficiency impossible to reach 100%.
The quality of the picking operation can be evaluated by the sorting efficiency η of the tailings, and the calculation formula is

IV. Selectability study of picking As mentioned above, it is necessary to conduct an ore selectivity test in order to accurately estimate the selected indicators quantitatively. [next]
All sorting machines are equipments for processing massive ore, and the processing capacity is high. Some sorting machines can process tens of tons and hundreds of tons per hour. It is not necessary to take a large amount of ore from the beginning to test on the sorting machine, but should first select the optional test on the laboratory equipment. To this end, before the formal test, take a few ore and waste rock that meet the sorting granularity to determine whether a sorting method is feasible. If it is affirmative, it is necessary to take 200~500 representative ore blocks for ore sortability test. At the same time, it is necessary to carry out a study on the particle size composition of the ore to determine the yield of each ore grade ore in the ore.
On the laboratory device, the weight and the content of the useful components are determined block by block according to the sorting characteristics (such as reflected voltage, activity, conductivity, etc.). The measurement results are divided into groups according to the order of the sorting characteristics (such as the magnitude of the reflected voltage value), and the weight of each group of ore and the grade of each group of ore are calculated according to the grade and sorting characteristics of the ore (also converted) Finished bits) draw two alternative curves. If the two optional curves (λ curves) are in good agreement, the sorting features can be sorted according to the selected sorting characteristics. After determining a beneficiation index (such as tailings grade), the theoretical other mineral processing indicators (such as concentrate grade, yield and tailings yield) can be obtained according to the curve; the obtained concentrate and tailings yield, multiplied The yield of the concentrate and tailings theoretically in the picking test is obtained by the selected fractions in the yield of the ore.
Due to various factors, the tailings yield actually sorted on the picker is always lower than the theoretical tailings yield. Therefore, in estimating the actual tailings yield, the theoretical tailings yield is multiplied by the tailings picking efficiency η. In order to finalize the necessity of setting up a picking plant and determine the various process indicators, it is usually necessary to take tens of tons or even hundreds of tons. The characterization of the ore is verified on the picker.

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