At present, most of the electrifications in the world are used for selected operations. Before the selection, the materials are generally re-elected or other mineral processing methods to obtain coarse concentrate. The use of electrification is to improve the concentrate grade and to obtain qualified concentrates, and the other is to separate the symbiotic minerals for comprehensive recovery, or both. Electrostatic separation now has grown to applications in other industries, in mineral processing is also part of practice for direct election ore, the main focus of this chapter is to introduce non-ferrous, rare and ferrous metals mining application electric separation practices.
1. The electro-selection of scheelite and cassiterite in non-ferrous metal ore often coexist, which is common in all tungsten mines in China (of course, mainly black tungsten ore), which are all pre-gravity The enrichment results in a mixed coarse concentrate, and the black tungsten ore is separated by strong magnetic separation, and the remaining part is a mixed ore mainly composed of white tungsten and cassiterite. Because the two have similar proportions (white tungsten 5.9~6.2; cassiterite 6.8~7.2), they are not magnetic, so the two methods can not be separated by re-election and magnetic separation. Generally, coarse particles are used for floating in the production, and fine particles are used for flotation. The effect is very poor and the efficiency is extremely low. However, the electrical properties of the two are significantly different. The scheelite has a dielectric constant of 5 to 6, a resistance of more than 10 12 Ω, a dielectric constant of cassiterite of 24 to 27, and a resistance of only about 10 9 Ω. For this reason, the use of electro-election is the most effective method, which is economical, simple in process, free of chemicals, and does not cause pollution. Therefore, most of the methods are used at home and abroad.
Domestic use of floating or flotation has long been used, and the actual use of electricity in production is after 1964. Under the conditions at that time, the electric sorting machine developed had only one Φ120 × 1500mm double-roller electric sorter, and this equipment was still used more frequently. Due to the influence of historical conditions, the efficiency of electro-selection is very low, and the process is complicated. The final concentrate quality and recovery rate are not ideal. In particular, only the coarser grains (greater than 60-100 mesh) of white tungsten can be sorted. Tin sill, but less than this size can not enter the electrification, and the return amount of the mine is very large.
The actual process of electrification of scheelite in a mine in Hunan is introduced. The plant uses a Φ120 × 1500mm double-roller electric separator (voltage 17.5kV), the flow of which is shown in Figure 1.
The raw material is the mixed coarse concentrate after re-election, and the sulfide ore is removed by lifting and floating, and then electrified after drying. When the material enters the power contained in the mineral is selected from: 70% scheelite, cassiterite about 15 to 20% hematite and limonite about 5%, bismuthinite 2%, 1% molybdenite about. In addition, there are a small amount of zircon, pyrite, sphalerite, fluorite, wolframite, bismuth and the like foam. Due to the desulfurization by the stage, the raw materials contain sulfur, phosphorus , arsenic and copper .
Figure 1 Flow chart of electrification of scheelite in a mine in Hunan [next]
The process test shows that the recovery rate of white tungsten is only about 60%, and the grade is as high as 74.51%, but the tin content in the white tungsten concentrate is often more than 0.2~0.3%, rarely less than 0.2%; the electrification of cassiterite can not be obtained. The concentrate must be subjected to secondary magnetic separation and re-election (magnetic separation to wolframite and other magnetic minerals), and the final tin concentrate has a grade of only 47.3% (Sn), and the recovery rate is about 90%, but contains WO. 3 is more than 20%, which is an unqualified concentrate.
For the white tungsten and cassiterite of the above mines, a large number of tests were carried out using DXJ type Φ320 × 900mm high-voltage electric separator. When the materials less than 1mm were electrified, the electro-election process was greatly simplified, only one time. Select high-quality scheelite concentrate, WO 3 ≥70% in scheelite concentrate, recovery rate of 90~95%, tin (Sn) less than 0.2%; -0.42+0.1mm The grain size is only one time. The WO 4 is 70.4%, the (Sn) is 0.14~0.18%, the ε WO3 is 96%, the cassiterite recovery rate is 96~97%, and the cassiterite grade is once. The selection can reach more than 40%. If the tin concentrate is selected once, the grade can reach more than 50%, and the recovery rate is 96%.
A selected factory in Guangdong also uses the above Φ120 × 1500mm double-roller electric separator. The raw materials come from the black and white tungsten coarse concentrate of each mine. The same is pre-screened into various levels, and then the black tungsten concentrate is separated by dry strong magnetic separation, and the remainder is white tungsten, cassiterite, sulfide ore, mica , apatite and quartz . The particles are floated to the sulfide ore, and then the white tungsten and the cassiterite are enriched by a shaker, and the obtained concentrate is dried and then electrified. The difference is that the material is divided into narrower grain sizes: -2+1.4, -1.4+0.83, -0.83+0.2 and -0.2mm. Each particle fraction enters the electrification separately, and the electro-optic process is generally the same as that of a certain mine in Hunan (five times of electrification), and finally the total scheelite concentrate contains WO 3 >65% and Sn is 0.2-0.3%. ε WO3 ≥ 80%.
Now the plant does not need Φ120 × 1500mm double-roller electric separator, and after using 60kV high-voltage electric separator, the amount of white tungsten concentrate is increased by about 20%, tin concentrate production is increased by 22%, and tin recovery rate is increased by 9.55%. It can be seen that the use of high-voltage electrification is more effective than the low-voltage electrification in the past.
Japan's Otani Mountain Concentrator, which treats coarse concentrates 60t per month, also uses electro-selection to sort scheelite and cassiterite. The raw material contains sulfide ore and is first removed by flotation. The equipment used is an electric separator with Φ125 × 500 and Φ125 × 1000mm and a voltage of 20kV. The raw materials are narrowly classified into individual particle sizes such as +10, -10+20, -20+40, -40+80, -80+150 mesh (or 180 mesh). The magnetic minerals are first removed by magnetic separation, and then electrified several times. Only the recovery rate of white tungsten was reported to be 95%, no white tungsten grade and its tin content and tin recovery rate and cassiterite grade were observed.
In addition, the Soviet Union has conducted a lot of research on stellite cassiterite containing various minerals in raw materials. The main raw material of cassiterite (Sn 9.7%) and scheelite (WO 3 7.9%), followed by titanium, iron, monazite, quartz, and the like. The particle size is 0.1~0.6mm, and the process flow combining electric and magnetic separation is adopted. After multiple sorting, the results are shown in Table 1.
product name | Yield,% | Product composition, % | Recovery rate,% | ||
锡石 | White tungsten | 锡石 | White tungsten | ||
Concentrate (conductor) Middle mine Tailings (non-conductor) Feed mine | 53.3 14.6 32.1 100.0 | 90.9 35.7 0.2 59.4 | 0.6 11.3 11.3 17.7 | 92.1 7.8 0.1 100.0 | 1.9 10.1 88.0 100.0 |
From the above results, the effect is not outstanding, and the finest grade can only reach 150 or 180 mesh. In addition, electrification can also be used for the selective separation of black and white tungsten ore.
Second, the elective of rare metal ore
(1) Electrification of ilmenite and rutile
Due to the needs and development of the military industry and the needs of other industries, the demand for ilmenite and rutile has increased. According to incomplete statistics of available data, the annual production of titanium concentrates in the world is more than 4.5 million tons.
Ilmenite and rutile are divided into primary ore deposits, terrestrial sand mines and coastal sand mines. However, regardless of primary ore deposits, they must be pre-enriched by gravity ore dressing and then electrified. Otherwise, it is extremely uneconomical. In addition, smelting and various industries require titanium concentrates containing more than 48% TiO 2 . The ilmenite from a factory in Sichuan was first re-elected, then dried by hot air, and classified by electric separation. The electric separator used was a Φ300 × 2000mm three-barrel high-pressure electric separator. The concentrate contained nearly 48% of TiO 2 . [next]
As far as the world is concerned, most of the ilmenite and rutile are currently recovered from coastal sand mines. This is currently the most important source, and production is now increasing. The first is the recovery of ilmenite and rutile in the coastal sand mines in Florida, USA. The annual production of titanium concentrates in the United States is over 400,000 tons. Since then, Australia has recovered titanium minerals from coastal sand mines, ranking first in the world, with at least 1.5 million tons per year. In recent years, there are eight companies in the country that use electricity to recover ilmenite and rutile. Sierra, West Africa, now produces 100,000 tons of rutile and ilmenite concentrate annually. In addition, the Soviet Union also used electro-selection to sort out the titanium concentrate of the sand mine, with an annual output of more than 100,000 tons. Other countries also recover titanium minerals from coastal sand or land sand ore, and the annual output is not low. China's coastal mines have a considerable amount of resources, and are currently concentrated in Hainan and Guangxi coastal areas of Guangdong, recycling a certain amount each year, but the output is not high.
The most prominent feature of seashore sand mines is that the minerals have been dissociated by the monomers, so there is no need for a large amount of operations such as crushing and grinding in the front. Generally, the weight of minerals per cubic meter of beach sand varies from 1 to 3 kg, and Another advantage is that the fine-grained grade (-150~200 mesh) is extremely low. These sea sands are coarse ore concentrates of the type containing magnetite, ilmenite, rutile, zircon and monazite, which were selected from the re-election plant on the waterfront, and then selected on the seashore or land. The electrification is the main selection method for qualified titanium concentrate, lead stone and monazite.
Figure 2 Flow chart of a factory in Guangdong
For example, the main coarse concentrate of a selected plant in the south is from Hainan Island. The raw materials are pre-extracted on the waterfront or land by re-election method, and then concentrated to the plant for selection. The TiO 2 containing titanium minerals in the raw materials of the selected plant is 30~38%, ZrO 2 is 6~7%, and the total rare earth TR 2 O 3 is 0.63~0.7%. The mineral composition is ilmenite, zircon, rutile, monazite, xenotime , magnetite, limonite, white titanium, and a small amount of cassiterite, gold, antimony ore. The gangue minerals are quartz, garnet , tourmaline , epidote, cross stone and kyanite. The process used is shown in Figure 2.
Since the raw materials come from various regions and the nature is also complicated, the process adopted is also complicated, but it has flexibility. The sorting indicators are shown in Table 2.
product name | grade,% | Recovery rate,% | Note | |||
TiO 2 | ZrO 2 | TR 2 R 3 | Y 2 O 3 | |||
Ilmenite Rutile Zircon Monazite Phosphorus Raw ore | 50 85 35 | 60~65 6.5 | 55 0.65 | 30 0.05 | 85 65 82 72 68 100 | 1. Rutile concentrate refers to high-titanium minerals composed of rutile, slate, sharp diamond and white titanium. 2. TiO 2 in the ore Refers to the total content. |
The electric separator used in the plant is a Φ120 × 1500mm double-roller electric separator (20kV). The selection of coastal sand mines in Australia mainly relies on electrification to obtain high-quality titanium concentrate, using the American Carpco high-voltage electric separator, and also magnetic selection and selection, and each year to obtain high-quality titanium concentrate 100000t. , rutile 65000t, zircon 9000t. [next]
Florida is famous for its titanium-producing concentrates. It is said to be very effective after using the Carpco-type high-voltage electric separator and the process flow of Figure 3. Â Â
Figure 3 Flow chart of the principle of electrifying sand mines in the United States
The ore is re-elected coarse concentrate or flotation coarse concentrate, containing 80~95% heavy minerals, and the ore size is -16+400 mesh. It is sorted by Carpco type electric separator, and the ore is preheated to $23. The processing capacity of each device is 14t/h; the maximum is 50t/h. The final concentrate obtained is calculated as titanium-containing minerals with a yield of 99% and a recovery rate of 98%. The index is relatively advanced.
(2) Electrification of antimony ore
There are many kinds of minerals containing antimony, and it is more meaningful to use antimony ore with high antimony. In the past 20 years, due to the development of the military industry, the demand for metal bismuth has increased, and the demand of other industries has increased, so the output has also increased. According to available materials, the world's annual production of antimony concentrates has exceeded 1,000 tons. Mineral tantalum-containing niobium power can not all selected separation, only tantalite, heavy tantalite, columbite, tantalum, manganese tantalite, niobium, titanium, tantalum, niobium, titanium, calcium, cerium, niobium ore and iron ore It has good conductivity and can be separated as a conductor in the electric selection, while pyrochlore and fine spar are poor conductors and cannot be separated by electric separation.
In the world, the ore grades of antimony ore produced in countries such as Nigeria and South Africa are high (more than an order of magnitude higher than domestic ones). In addition, Malaysia, the Philippines, India and Thailand also recover a portion of the coltan from the sand mine. The content of the ore is not high, and the production of the Soviet Union is also growing, and the research and production in this area are highly valued.
China's antimony ore has many resources, some of which are Weijing granite primary deposits, and some of which are Weijing granite weathered deposits and sand deposits. Most of them use re-elected shakers to concentrate on coarse concentrates, and then use magnetic and electric separation. Choose to obtain the final antimony concentrate. At present, domestic demand for concentrates contains (Ta, Nb) 2 O 5 > 40%, and tantalum (Ta 2 O 5 ) is higher than 20%, but the proportion of ore that is currently mined is higher than that of tantalite. Big, and the performance of the cockroach is far worse.
According to the situation in China, the coarse concentrate obtained from the re-election of the original ore is about 2~4% (Ta, Nb)-2O 5 , and contains a large amount of gangue minerals such as pyrite, tourmaline and bubble ore. It is garnet, followed by quartz, feldspar and mica. The use of strong magnetic separation efficiency is not high, mainly garnet is also a weak magnetic mineral, its magnetic is similar to the antimony ore, it is difficult to effectively separate them. The Φ120 × 1500mm high-voltage electric separator has poor sorting effect or can not be sorted.
DXJ type Φ320 × 900mm high pressure drum type electric separator has been applied in some domestic antimony ore (such as Xinjiang Concentrator), and generally achieved good results. Because in the coarse concentrate, the antimony ore belongs to the conductor ore, and a large number of garnet, quartz, feldspar, mica and zircon are all non-conductor mines, so they can be effectively separated by electro-election. The process and results of sorting the high pressure electric separator into the antimony ore are shown in Figure 4 and Table 3.
Figure 4 Yankuang electrification process
name | Yield,% | Grade (TaNb) 2 O 5 | Recovery rate,% | Note |
Concentrate Middle mine Tailings total | 6.51 7.21 86.37 100.0 | 43.21 2.71 0.44 3.387 | 83.01 5.71 11.28 100.0 | The ore is the crude concentrate obtained after re-election |
The following is a description of the actual production process of the Soviet coltan, which is symbiotic with other minerals such as cassiterite, zircon, ilmenite, garnet and monazite. The ore is a sand ore and is re-elected to give heavy minerals. The drum type electric separator is matched with the strong magnetic separator, and the shaker is used for re-selection to obtain qualified antimony concentrate. The process is shown in Figure 5.
Figure 5 Flow chart of the process of mineral processing in the Soviet coltan
Tinfoil grade Sn=49% ε =85~87%
Ilmenite content (referring to minerals) 96% ε = 94~96%
The electric separator CÐC-1000 drum type electric separator is used, and the ore heating temperature is 80-120 ° C, and the sorting granularity is less than 1 mm. For the electrification operation, the recovery rate of the sputum operation is 94.15%, the recovery rate of the cassiterite operation is 97.49%, and the recovery rate of the zircon operation is 93.89% (both minerals).
Some sand ore dressing plants in Guangdong and other places in China have similar minerals. The processes and equipment used are basically the same, and the ore dressing indicators are different. The difference between China and the Soviet Union is that there are too many strontium ore deposits, and there are fewer such deposits with high enthalpy.
Third, the selection of ferrous metal iron ore
Iron ore is electrified and is currently selected mainly. The largest production plant is known as the Wabush plant in Canada, followed by the Malmberget plant in Sweden.
(1) Iron ore electrification in the Wabush plant in Canada
The iron ore is first crushed, ground and re-elected (particle size is -0.6mm0). After re-selecting the concentrate, it is further selected by electro-election to obtain ultra-pure concentrate. The equipment used is the American Carpco industrial production type electric separator (58 sets). The process flow and beneficiation index are shown in Figure 6.
Figure 6 Canada Wabush plant production flow chart [next]
According to the process, the processing capacity is 850 tons per hour, and it is currently the largest concentrator in the industry. After electro-election, the grade of iron concentrate is increased from 65% to 67.5%, and the content of SiO 2 in concentrate is reduced to 2.25%. Electro-election is the most effective method to reduce SiO 2 . It is advantageous to use electricity to remove 50% of SiO 2 because it can save coke , energy, labor and other auxiliary materials, and can also increase the utilization factor of the blast furnace. It is undeniable that the drying of raw materials also requires energy, but the cost of the plant has been reduced by 25% from various aspects (including concentrate transportation, etc.).
(II) Electrification of iron ore in the Swedish Malmberget plant
The plant produced high-grade hematite concentrates before 1972, similarly using the Mabush method. In addition to reducing the SiO 2 content, it is also important to reduce the phosphorus content in iron concentrates by this method. It proves to be very effective, producing 1 million tons of ultra-pure concentrate per year.
The beneficiation process of the drum type high-voltage electric separator is shown in Fig. 7. In addition, the United States and the Soviet Union have also carried out research on the process of iron ore selection and direct electrification, which proves that this method can greatly reduce the content of SiO 2 and phosphorus (P) and obtain high quality iron concentrate. Similar tests have been carried out in China to improve the grade of iron concentrate and reduce the SiO 2 content.
Figure 7 Swedish Malmberget electrification selected iron ore flow chart
4. Electrification of other ores (1) Selection of gold
For sand gold mines, the use of electric selection is also a very effective method. The gold ore mine is re-elected (shaker or chute, spiral sorting machine, etc.) to enrich the heavy minerals, and then magnetic matching and electric selection are used to improve the gold grade. China has tested a mine and achieved remarkable results.
The ore (particle size is -2mm) is selected by shaker, containing 120.36g/t of gold. The heavy sand mineral is: magnetite 30%, ilmenite 10% quartz, feldspar 25%, zircon 7%, angle Amphibole 10%, monazite 3%, limonite 8%, garnet 2%, other mica, tourmaline and so on. When entering the electrification, the materials are divided into two levels of +70 and -70 mesh.
The electric selection process is relatively simple, and both use one rough selection and one sweep. It is proved that the magnetic separation tailings adopt high-voltage electric selection, which can make the gold recovery rate reach 93.91%, and the gold entering the electrification is 387.22g/t. After electrification, the +70 mesh and -70 mesh gold concentrates can be enriched to 13480.93g. /t, the medium mine is 1147.38f/t. If the middle mine is further electrified, the gold recovery rate can be further improved.
After the magnetic product was separated by magneto-wetting, the crude gold concentrate was 24.13 g/t using the nearly identical procedure described above, and the medium ore and tailings did not contain gold.
The selection process is shown in Figure 8.
Figure 8 Sand gold mine selection flow chart [next]
It is clear from the above simple process test that the heavy sand mineral of a gold deposit is matched by magnetic separation and high voltage electric selection. The sorting effect is very significant. When the magnetic separation tailings are electrified, the original ore contains gold 387.22g/ t, after electrification, the gold concentrate can be enriched to 13480.93g/t, and the recovery rate can reach 93.91%; the gold content of the mine in the sweeping selection is 1147.38g/t, and the recovery rate is 5.24%.
(II) Electrification of other ores Currently, the application range of electrification is expanding. For example, the Soviet Union, the United States and Canada use electro-selection to separate feldspar and quartz. The content of potassium and sodium in feldspar is 11~12%. Etc., they are used in industrial production. The United States and the United Kingdom also use electricity to sort and select potassium salts , and there are many patents. In addition, apatite and quartz are sorted by contact charging.
V. Factors affecting electrification
There are many factors affecting electrification, but they can be summarized into two aspects, one is the various factors of the electric separator itself, and the other is the requirements for materials (ie, the requirements for preparation work).
(1) Factors of the electric separator itself 1. Voltage The voltage of the electric selection is very important and directly affects the electrification effect. In the past, the voltages used in countries around the world were mostly around 20kV. From the theory and the actual, it is concluded that increasing the voltage is beneficial to the sorting effect. The charge obtained by the ore particles is directly related to the field strength. The higher the voltage, the greater the field strength. The more electrons that escape from the corona, the more favorable the sorting, but we cannot generally think that the higher the higher the voltage, the better. Because the sorting voltage required for each specific mineral is also different. When it is too low, it is proved in the experiment that some minerals such as antimony ore are less than 5kV/cm, and it is impossible or difficult to sort effectively; when it is too high, it will affect the recovery rate of the conductor ore.
Table 4 shows the results of voltage experiments for the study of -40+150 mesh white tungsten and cassiterite.
Voltage, ten thousand volts | product name | Yield,% | grade,% | Recovery rate,% | Note | ||
WO 3 | Sn | WO 3 | Sn | ||||
1.3 | Conductor Nonconductor Raw ore | 25.65 74.35 100.00 | 53.70 69.10 65.147 | 16.70 0.60 4.729 | 21.14 78.86 100.00 | 90.57 9.43 100.00 | Pole distance L=60mm drum speed N=80r/minΦ320 × 900mm electric separator test data |
2.4 | Conductor Nonconductor Raw ore | 18.84 81.16 100.00 | 43.82 70.09 65.14 | 24.10 0.22 4.720 | 12.67 87.33 100.00 | 96.18 3.82 100.00 | |
3.0 | Conductor Nonconductor Raw ore | 14.14 85.86 100.00 | 33.70 70.32 65.14 | 32.14 0.22 4.733 | 7.32 95.86 100.00 | 96.0 3.11 100.00 | |
3.6 | Conductor Nonconductor Raw ore | 13.05 86.95 100.00 | 34.00 69.81 65.136 | 32.71 0.53 4.729 | 6.18 93.19 100.00 | 90.26 9.74 100.00 | |
It can be seen from the table that the sorting effect is most significant when the voltage is 30kV (5kV/cm). Near-qualified white tungsten concentrate can be obtained by one electrification. The recovery rate of cassiterite is 96%, and the recovery rate of white tungsten is 93%.
In addition, in the selection of a certain beach sand mine, it is also obvious that high-quality titanium concentrate, when the voltage is lower than 40kV (6.7kV / cm), it is impossible to obtain titanium containing more than 48% TiO 2 Concentrates, the selection of antimony ore below 40~50kV can not be effectively sorted.
2. Electrode structure and its position relative to the drum The electrode structure refers to the number of corona poles and the position and the magnitude of the poles. Many countries have studied this. The first electric sorter produced by Sturtevent in the UK has only one. The root corona pole, and then further developed into the electrode structure form of the domestic Φ120 × 1500mm electric separator introduced above, all using a small drum diameter, and later the United States has improved, combining a corona pole and a polarized pole Installed together, the Soviet Union and other countries use multiple corona poles without static electrodes. The DXJ-type drum-type electric separator developed in China uses a combination of multiple corona poles and one pole-polar electrode structure. The Carpco electrode, which is a combination of two static electrodes and a corona electrode, improves the electrode structure and correspondingly improves the beneficiation effect. According to the author's long-term experiments and examinations, the recovery rate of a single corona pole and a partial polar dressing is relatively high, but the concentrate grade is low and the sorting efficiency is very low. There are too many coronas, which are only good for improving the concentrate grade, and the recovery rate of the conductor is unfavorable. The relative position of the corona pole and the drum is about 45°.
The pole distance is also an important factor in the selection of electricity. The voltage required for the small pole pitch is low, but it is difficult to achieve in production because it is easy to cause spark discharge and affect the beneficiation effect. With a pole pitch of 60~80mm, at a higher voltage, it is not easy to cause spark discharge, and can ensure the beneficiation effect.
3. Drum speed The drum speed is also one of the important factors affecting the electrification effect. This is essentially a matter of time when the material is passed through the electric field. It must be pointed out that the time of the material passing through the electric field should be close to 0.1s to ensure that the material can obtain sufficient charge, otherwise the sorting efficiency will be reduced. The speed is also directly related to the particle size of the selected material. The material has large particle size, requires slow rotation speed, fine particle size and requires fast rotation speed. This is because the coarse fraction is more charged at a slower speed through the electric field, and for a non-conductor, a larger specular suction can be generated, so that it is less likely to fall into the conductor ore. If the rotation speed is too large, the centrifugal force of the conductor or non-conductor ore will increase, causing the non-conducting ore particles to leave the drum surface prematurely, which is mixed in the conductor product. Table 5 is the sorting of -40+150 mesh white tungsten and cassiterite. Results of different speeds (one sorting). [next]
Speed ​​r/min (or m/min) | product name | Yield,% | grade,% | Recovery rate,% | Note | ||
WO 3 | Sn | WO 3 | Sn | ||||
(70) 70.35 | Conductor Nonconductor Raw ore | 13 87 100 | 30.26 70.35 65.138 | 33.41 0.45 4.734 | 6.04 93.96 100.00 | 91.73 8.27 100.00 | Φ320 × 900mm high-voltage electric separator, the pole distance l is 60mm, the voltage is 30kV, the conductor is cassiterite, and the non-conductor is scheelite concentrate. |
(80)80.0 | Conductor Nonconductor Raw ore | 16.4 83.6 100.0 | 39.64 70.14 65.14 | 27.98 0.17 4.731 | 9.98 90.02 100.00 | 97.00 3.00 100.00 | |
Conductor Nonconductor Raw ore | 18.8 81.2 100.0 | 43.64 70.13 65.15 | 24.16 0.22 4.72 | 12.62 87.38 100.00 | 96.22 3.78 100.00 | ||
Conductor Nonconductor Raw ore | 38.2 61.8 100.0 | 59.51 68.61 65.33 | 11.56 0.51 4.731 | 34.82 65.18 100.00 | 93.34 6.66 100.00 | ||
Obviously, the lower the rotational speed, the higher the conductor grade, and the non-conductor is rarely mixed in the conductor. Conversely, at high speeds, the lower the conductor grade, the lower the non-conductor is easily mixed in the conductor, and the non-conductor grade is high.
The speed should be different depending on the job requirements. When the conductor product is concentrate, the sweeping operation should use high speed to ensure the recovery rate of the conductor as much as possible. In order to ensure the conductor grade during the selected operation, low speed should be used.
4. Location of the ore plate In addition to the above influencing factors, the location of the ore plate also directly affects the quality and quantity of the concentrate. Therefore, the appropriate location should be selected according to the job requirements. If the non-conductor ore is required to be very pure, the second sub-salt plate under the drum should be tilted to the left to return the middle mine to re-election; otherwise, if the conductor (concentrate) is very pure, the first sub-mine The plate is tilted as far as possible to the right to re-select the middle mine.
(2) Requirements for materials before electrification
1. Particle size composition of the material Due to the centrifugal force and gravity component of the ore particles when sorting on the drum type electric sorter, in general, the more uniform the material size, the better the effect, but there is a production practice. A big contradiction, that is, the narrower the grain size, the stricter the classification and classification, the increase of the process, and the generation of dust. Therefore, under the conditions that basically meet the requirements, the screening classification should be reduced as much as possible or not. Another method to solve this contradiction is to use a multi-drum electric separator, the first drum above is only used for classification. The following drums are used for sorting.
At present, the particle size range of the electroless ore is better than 2~0.1mm, and the most suitable treatment particle size is -1~0.1mm. The smaller the particle size, the worse the effect.
2. Material heating When the ore contains moisture, it will seriously affect the sorting effect, because the non-conductor improves the conductivity and is easily mixed in the conductor product. For this reason, it is very important to warm up in advance. The purpose of warming and drying is to remove the surface moisture of the ore, restore the inherent electrical properties of different minerals, and loosen the material. However, heating is also different depending on the ore. It is not possible to uniformly stipulate the temperature. Sometimes the heating is too high, but it causes bad consequences. For example, when sorting with garnet and garnet, when heating exceeds 300 °C, the non-conductor garnet The conductivity is increased, making sorting more difficult. Another example is the separation of white tungsten and cassiterite in some mines. We found that 200 °C is the most suitable, and the temperature is too low and too high to make the sorting effect worse. The relationship between the test results and temperature is shown in Fig. 9.
Figure 9
Obviously, the grade of the conductor mineral (cassiterite) increases with the increase of temperature, and the tin content of the non-conductor mineral (white tungsten) is the lowest at 200 ° C. The high-quality scheelite concentrate can be obtained by one sorting at this time. The grade of the mine is also the highest, reaching more than 40%, and the recovery rate is also the highest, reaching 96.6%. If the temperature is further increased to 300 ° C, the tin content in whit Underground Work Mining Tricycle,Heavy Load Cargo Dump Truck,Mini Dump Truck Electric FengXian Enland International Trading Co.,LTD , https://www.enlandvehicle.com