Spiral chute concentrator structure and working principle
The structure of the spiral chute concentrator is shown in Figure 1. It is made the spiral by a bending chute around the vertical axis, the spiral has 3 to 5 circles, fixed on a vertical support, the spiral groove section is a parabolic or elliptical part, the bottom of the groove in the longitudinal (along the direction of the flow of ore) and transverse (radial) have a certain degree of inclination.
Starting from the second circle, there are heavy product discharge pipes (4-6 in total) in the middle part of the bottom trough, and the upper part of the discharge pipe is equipped with a cutter, which can intercept the heavy mineral flow and make it enter the discharge pipe, and the two scrapers of the cutter are pressed on the trough surface, and the movable scraper can be rotated to adjust the size of the opening angle between the two scrapers, so as to adjust the discharge amount of heavy minerals, as shown in Figure 2. In order to improve the quality of the heavy product, there are several water filling points at the inner edge of the trough, called washing water, which is fed into the inner edge of the trough by the central water pipe through a valve.
When sorting, the slurry is fed evenly from the upper part of the tank along the width of the tank, and the slurry is stratified in the process of flowing along the tank, the heavy minerals enter the bottom layer and move to the inner edge of the tank under the combined effect of various forces; the light minerals are thrown to the outer edge in the rapid rotary motion. As a result, the mineral grains with different densities are separated in the lateral direction of the trough, as shown in Figure 3. The heavy minerals flowing along the inner edge of the trough are intercepted by the interceptor and discharged through the discharge pipe, with the highest quality of the heavy product obtained from the first to the second discharge pipe above and the lower quality of the heavy product below. The washing water added at the inner edge of the trough flushes some of the lighter minerals entrained in the heavy product to the outer edge, which helps to improve the quality of the concentrate. The tailings are discharged from the end of the lowermost trough.
Operation points of the spiral concentrator
(1) The maximum feed size is 6mm. If too large pieces of ore enter, it will disturb the ore flow and block the concentrate discharge pipe. Large flaky pebbles are also detrimental to the separation. Therefore, it is necessary to grate out the large pieces with a screen before sorting. In addition, when the selected material contains more mud, it will make the sorting effect become bad, so when it contains more mud, it should be deslimed in advance.
(2) Control the amount of mineral feeding. When the fine size concentrate contains more mud, the amount of mineral feeding can be smaller; when coarse concentrate contains less mud, the amount of mineral feeding can be larger. The quality fraction of the feed is not strict, the quality fraction in the range of 10% to 30% do not have significant changes of the selection index.
(3) Washing should be scattered from the inner edge of the supply, so as not to disrupt the flow of mineral. When washing water is large, it has high concentrate grade, but the recovery rate is reduced; When washing water is small, it improves the recovery rate, washing water from the top to the bottom should be increased gradually.
(4) The concentrate rate is adjusted by turning the movable scraper of the interceptor, and the concentrate grade will be reduced when there are too many intercepted concentrates. The suitable position of the movable scraper should be determined by sampling examination, and then be flexible after having experience.
Advantages and disadvantages of spiral chute concentrator
Spiral chute concentrator is widely used in separating hematite, recovering heavy minerals from tailings and separating rare metals and non-ferrous minerals because it has the following advantages:
①no running parts, no power consumption;
②small area needed for the equipment, large processing capacity;
③high feed quality fraction but less washing water consumption, so it is water saving;
④The operating conditions (such as feed size, quality fraction, etc.) are not demanding, and the separation index is more stable.
⑤Work around the clock without stop.
The disadvantage is that the equipment height difference is large and often requires a sand pump to lift the slurry in order to feed the ore. In addition, the concentrate grade is slightly lower, it is good for rough or primary concentration. It will achieve better results to work with the shaking tables in a mineral process plant.