What reagents are needed for tungsten-tin ore gravity separation?

The beneficiation method of tin ore is determined by its own characteristics. As mentioned above, most of the tin concentrates produced in the world are produced from cassiterite deposits, and the density of cassiterite is higher than that of raw ore. Therefore, tin ore is traditional.

The mineral processing technology is gravity separation and gravity separation. However, with the passage of time, the particle size of cassiterite in the selected ore becomes smaller and smaller, resulting in cassiterite flotation process and selective flocculation process. In addition, because tin minerals often contain various

Iron oxide minerals include magnetite, hematite and limonite, which cannot be well separated from cassiterite by flotation and gravity separation. Therefore, in recent years, magnetic separation has appeared in the process of tin ore dressing. This magnetic separation operation

The main purpose is to separate tin and iron, which is different from the dry magnetic separation process for separating tungsten and tin. In a word, the beneficiation method of tin ore has broken through the traditional single gravity separation process and entered a new era of combined use of various beneficiation methods.

Period. Nevertheless, gravity separation is still the main method of tin ore dressing.

China's tin beneficiation technology ranks among the top in the world, and its characteristics are as follows:

1. Raw ore treatment

The raw ore treatment of tin concentrator can be roughly divided into the following contents: ore washing, desliming, crushing, screening, batching, pulp preparation, dense medium pre-selection and so on. For different plants, or all the contents, or only some of them. Now choose the key points as follows:

Desliming operation is the key operation in gravity separation process, which directly affects the separation index. More than 80% of the raw ore in China's existing concentrator is placer tin ore. There are 40-60$%- 10 in the raw ore of Yunxi placer.

Fine-grained slime is the interference factor of any mineral processing method. Desliming operation is actually divided into two stages, one is the dissociation and dispersion of ore mud, and the other is the separation of mud and sand. These two stages can

You can do it separately or at the same time. The main purpose of desliming is to dissociate and disperse the fine mud of coarse particles and mud balls mixed in the fine mud. At present, the desliming equipment used in China includes water guns and various ore washers.

Wait a minute. After screening, the dispersed coal slime can be directly removed by 125mm (or 75mm) hydrocyclone (sludge is removed first and then classified); More is through the large diameter cyclone separator (250 mm or

500 mm), overflow with the small diameter cyclone desliming (classification first and then desliming). In foreign countries, the diameter of desliming cyclone used is as small as 50 mm or even 25 mm

In recent years, dense medium preconcentration has been applied in tin concentrator at home and abroad. Both Dachang in Guangxi and Gejiu in Yunnan have adopted this process. This method is also used in important tin concentrators such as Australia, Bolivia and Britain. It is widely used in China.

Heavy medium cyclone. The D.W.P classifier has been developed abroad, and the effect is very good. The economic benefit of dense medium pre-selection mainly depends on the waste removal rate. Generally speaking, if the waste removal rate is lower than 20-25%, it has no economic value.

In addition, cone concentrator is sometimes used as preselection equipment.

2. Classification of ores

Multi-stage grinding and multi-stage separation process is generally used in tin ore dressing, because cassiterite is fragile and more easily broken than other raw ores. The number of segments is generally two to four.

From the process point of view, if sulfide needs to be removed, there is a problem of desulfurization first or later, one desulfurization or multiple desulfurization, depending on the nature of the ore. In the tin selection system itself, press.

According to China's experience, a secondary concentrate is produced between the shaking table concentrate and the middling, and it is called "secondary concentrate concentration and washing" for centralized treatment. Except for some monomer cassiterite, most of the secondary concentrates are iron-tin combinations with large particle size.

Rough. This part of the material is separated from the main process through the re-washing process, and ground and separated respectively. Therefore, this part of materials with high iron content cannot be mixed with ordinary middling, which affects the separation of middling. On the other hand, it also

The separation efficiency of secondary concentrate is improved.

Ore sorting equipment mainly includes jig and vibrating screen, and some use various types of chutes.

Another main problem of mineral processing system is how to reduce the excessive crushing of cassiterite. The key to solve the problem is to try to prevent cassiterite that has become a monomer from being reground. At present, multi-stage grinding, multi-stage separation and fine screening are all feasible schemes as closed-circuit equipment for grinding.

Narrow classification is also a successful experience of tin beneficiation in China.

3. Treatment of coal slime

China has accumulated rich experience in slime treatment and reached the international advanced level.

The coal slime treatment process is divided into two parts: coal slime pretreatment and coal slime separation.

Coal slime pretreatment includes concentration (returning to the team) and coal slime concentration. , to ensure a balanced quantity and stable quality (particle size, concentration, etc. ) ore into the slime separation system.

Since the mid-1960s, the tin slime treatment process consisting of a series of slime separation equipment developed by China has attracted international attention. The core part of this process is centrifugal belt.

Chute-a shale shaker with a trough from which the final concentrate is obtained. In addition, according to the recent progress, it is becoming a reality that only two centrifuges can be used to obtain poor middling or even rich middling.

After 20 years' changes, this tin slime treatment process with China characteristics is now in a more perfect stage. At the same time, foreign equipment and processes for treating coal slime are constantly emerging, such as small-diameter hydrocyclones.

，bath elet &； Application of motzley turnover bed, cross-flow belt and cassiterite flotation process. China is also gradually introducing and digesting these new equipment and processes, which makes the slime treatment process more and more perfect.

4. cassiterite flotation

Cassiterite flotation appeared 60 years ago. The first cassiterite flotation workshop (50 tons/day) established in Germany with oleic acid as collector was put into operation on 1938. It has been 50 years since then, but cassiterite is still in flotation.

The separation process is not widely used in production, and the number of cassiterite flotation workshops that have been put into production is very small. The reason is that the cost of reagents is too high, and the influence of reagent toxicity on the environment can not be ignored. However, as far as mineral processing technology itself is concerned,

In a word, cassiterite flotation process has made progress, especially in new flotation reagents, which have opened up a wider field, especially the emergence of arsenic acid and cassiterite phosphonate flotation reagents (typical examples are toluene swelling acid and styrene).

Phosphonic acid), so that the flotation efficiency has been significantly improved. China has successively established cassiterite flotation workshops in Yunnan and Guangxi, among which Guangxi Changpo concentrator has built a cassiterite flotation plant at 1975, with a processing capacity of 100 tons/day.

Toluene arsonic acid was used as collector, and the tin grade of feed was 0.6%, the tin grade of concentrate was 25%, and the tin recovery rate was 65%.

Although there are some problems in cassiterite flotation practice at present, with the development of technology and economy, cassiterite flotation, as one of tin beneficiation methods, will be more widely used.

5. Magnetic separation

The wet high-intensity magnetic separator made great progress in iron ore beneficiation in the early 1970s, and was soon introduced into tin beneficiation process, which increasingly showed its important role in tin beneficiation.

In the process of tin beneficiation, it can generally be used in three parts:

(1) magnetic separation of raw ore

After preparation, the raw ore is magnetically separated before entering the separation operation. In a sense, this can also be called magnetic classification (as opposed to classification by particle size). Feeding the obtained non-magnetic part and magnetic part into a reactor respectively.

Enter the main process of reselection. Among them, the non-magnetic part is easy to handle and can obtain higher recovery rate and concentrate grade, while the magnetic part is difficult to separate, so it is not necessary to force high-quality products, but to produce more rich and even poor middling.

The order of other parts is also roughly the same.

(2) magnetic separation of secondary concentrate

As mentioned above, there are many iron-bearing minerals in the secondary concentrate, which is a good place for magnetic separation to play a role.

(3) magnetic separation of concentrate

Magnetic separation is arranged in the above two parts, which requires cassiterite to be separated from iron minerals as much as possible. However, this contradicts the purpose of reducing excessive crushing of cassiterite and is often ignored. After iron minerals enter the concentrate in combination, they can be ground more fully, and there is relatively little concern about cassiterite crushing. So in practice, this scheme is accepted by more people.