Nielsen concentrator

I. Introduction
With the rapid development of mining industry, countries around the world have paid more attention to resource utilization and environmental pollution. This has raised a new topic for mineral processing experts - the development of high-efficiency, non-polluting mineral processing technology and equipment.
Gravity beneficiation is a traditional beneficiation method that does not require the addition of any chemical agents and has the advantage of being non-polluting. The disadvantage is that the enrichment ratio is not high, the quality of the concentrate can not meet the needs of smelting (such as jigging, chute, heavy medium dressing, etc.); or the production capacity is small (such as a shaker), these shortcomings restrict the development of re-election. And the expansion of the application field.
In this new situation, Mr. Byron Knelson of Canada used the "enhanced gravity" produced by centrifugation (in order to expand the difference in specific gravity between light and heavy minerals) and the addition of a counter-flush loose mineral bed. The method was organically combined and successfully developed the “Nielsen Concentrator” named after its surname. He successfully solved the problem that the heavy mineral bed existing in various centrifugal concentrators is rapidly crushed, and there is not enough sorting space and sorting time. The enrichment ratio of gold is increased from 20-100 to 1000~ from conventional re-election equipment . 5000; and processing capacity is also very large, the latest 70-inch Nielsen concentrator reached 650t / h · Taiwan. Because it absorbs the essence of conventional re-election equipment, eliminates its shortcomings, and incorporates many unique patent ideas, it is naturally favored by countries all over the world. Since it was put into industrial application in 1978, it has been used in more than 70 countries including Canada, Australia, South Africa and Russia, with more than 2,700 sets installed. China's Shandong Yingezhuang gold mine, Henan Jinqu gold mine, Shanxi Fanyu gold mine have also been successfully applied.
   Second, Nielsen concentrator structure, sorting principle and process, process parameters
(1) Nielsen concentrator construction
The machine consists of sorting cones, feeding pipes, discharging pipes, driving devices, water supply devices, automatic control systems, etc., and they are combined and fixed in a frame to form a complete beneficiation equipment (Figure 1). The core component of the machine is a sorting cone. It is made of highly wear-resistant polyurethane. There is a ring groove with a gradually increasing diameter from the bottom to the top of the cone. The number of fluidized holes in the ring is distributed. , size, and location are designed based on a large number of research results. There is also a concentric outer casing outside the sorting cone, and the space between the outer casing and the cone forms a water chamber.
Figure 1 Nielsen concentrator construction diagram
1-sorting cone; 2-slurry distribution plate; 3-feed pipe;
4-row ore cone; 5-water chamber; 6-concentrate discharge tube
(2) Principle of sorting
The Nielsen concentrator is an intensified gravity centrifugal beneficiation plant based on the centrifugal principle. In the enhanced gravity field generated by centrifugal force, the difference in specific gravity between light and heavy minerals is amplified (for example, the density of 1 unit volume of quartz and natural gold in the ordinary gravity field (1G) is 2.7 and 19 g/cm 3 , respectively. The difference is 16.3 g/cm 3 ; and the density in the 60 G centrifugal field is 162 and 1140 g/cm 3 , respectively, and the difference is expanded to 978 g/cm 3 , which is 60 times larger.), the sorting is easier to carry out; On the one hand, the fluidized water makes the bed loose, and the light minerals in the bed are continuously taken away by the recoil. The newly added heavy mineral fills the space left by the light minerals leaving, making the concentrate in the ring ditch. Continuous improving. The combination of the above two points has laid a theoretical foundation for improving the sorting efficiency of the Nielsen concentrator.
(3) Sorting process
The slurry is fed from the top to the lower distribution plate by the feeding pipe, centrifugal force throws it onto the wall of the sorting cone, and the ring groove is quickly filled from bottom to top, so that the enriched bed is formed. At the same time, the fluidized flushing water enters the water chamber from the lower part through the hollow rotating shaft, and enters the annular groove in the sorting cone in a counterclockwise direction along the tangential line under pressure (Fig. 2). When the heavy mineral particles are subjected to centrifugal force greater than the inward flushing water pressure, the particles are deposited in the annular groove; conversely, the light minerals enter the tailings from the upper part of the sorting cone under the impulse of the flushing water and the new incoming slurry. Discharge after the tube. In the continuous loose bed, heavy mineral particles are continuously deposited in the annular groove, while light minerals are continuously removed from the bed. When the ring is filled with heavy minerals, the semi-continuous Nielsen concentrator needs to stop feeding for a few minutes to flush the concentrate out of the ditch. In addition, there is a continuous variable-discharge type Nielsen machine (CVD) that can be used at any time. Adjust the size of the concentrate and continuously discharge the concentrate.
Figure 2 Sectional view of the sorting cone ring
(4) Process parameters
The process parameters used in the semi-continuous mining industrial Nielsen concentrator are listed in Table 1.
Table 1 Process parameters of semi-continuous mining industrial Nielsen concentrator
model
General amount of minerals
/t·h -1
Fluidized water
/m 3 ·h -1
Maximum slurry volume / m 3 ·h -1
Maximum feed size / mm
The most suitable mineral size / mm
Concentrate weight
/kg
Equipment net weight / kg
Motor Power
/kW
KC-XD70
KC-XD48
KC-30
KC-20
KC-CD12
KC-CD10
650
100~300
50~100
10~50
8~10
0.9 to 8
68～125
41～61
17~25
8~14
4.1 to 5.7
3.4~4.5
900
400
135
70
15
10
6
6
6
6
6
6
1.7
1.7
1.7
1.7
1.7
1.7
100~40
45~50
20~27
7 to 10
2.5 to 4.5
2.0 to 3.8
18150
5680
1724
1000
263
201
150~375
30～75
11
5.5
1.5
1.1

Brake Valve

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