Is the flotation processing ineffective? Have you taken these eight factors into consideration?

In the process of flotation by flotation machine, there are many factors affecting the flotation effect, including iradjustable factors and adjustable factors. Non-adjustable factors refer to the nature of ore. Adjustable factors include grinding fineness, pulp concentration, pulp acidity and alkalinity, reagent system (prescription), pulp temperature, water quality, flotation time, etc. Do you know how these factors affect the flotation process?
flotation machine

1. Ore properties


Ore properties mainly include chemical composition, mineral composition, structure and structure, occurrence state of useful and harmful elements, physical and chemical properties of ore, etc. The fluctuation of raw ore grade will increase the difficulty of controlling flotation process conditions. Among them, the oxidation rate of ore has a great influence on flotation, mainly as follows:

A. The oxidation of metal minerals and gangue minerals will change the original mineral and ore structure, forming a series of soil or clay minerals, which will greatly increase the amount of slime.
B. Owing to oxidation, mineral composition in ores will become more complex, and their surface physical and chemical properties will also change. The original flotation process must be changed.
C. different oxidation degree of ore will affect pulp pH, thus affecting the type and dosage of flotation agent.

2. Grinding fineness


Grinding fineness is an adjustable factor, which is mainly achieved by grinding operation. The suitable grinding size should be determined according to the distribution size of the useful minerals in the beneficiation test results, so that the useful minerals and gangue can be basically dissociated and the associated minerals and gangue can be minimized. For coarse-grained monomer minerals, grinding fineness must also be less than the upper limit of mineral floatation size. For example, the upper limit of sulfide flotation is 0.25-0.3 mm, gold-bearing pyrite is 0.2 mm, and monomer gold is more than 0.5 mm, it can hardly float and should be controlled below 0.25 mm.

It should be noted that too fine grinding particle size of ore also has a negative impact on flotation process (i.e. over-grinding and mud effect). Generally, when grinding fineness is less than 0.01 mm, flotation index decreases significantly; when grinding fineness is less than 2-5 micron, useful minerals and gangue minerals can hardly be separated. Therefore, the selection of appropriate grinding fineness is of decisive significance to the flotation process effect.

3. Pulp Concentration


The influence of pulp concentration on flotation process is mainly reflected in the following aspects:

A. recovery rate
There are obvious regularities between pulp concentration and recovery in various mineral flotation. When the pulp is very thin, the recovery rate is low. When the pulp concentration increases gradually, the recovery rate will increase gradually and reach the maximum. When the optimum pulp concentration is exceeded, the recovery rate will decrease again.
B. Concentrate quality
In general, the concentrate quality is high when flotation is carried out in a thinner pulp. When flotation is carried out in higher pulp, the quality of concentrate is low.
C. Pharmaceutical dosage
In the flotation process, the pulp must maintain a certain concentration of reagents in order to obtain good flotation process indicators. When the pulp is thicker, the concentration of liquid-phase herbal medicine increases, and the dosage of herbal medicine per ton of ore can be reduced. On the contrary, when the pulp is thinner, the dosage of herbal medicine per ton of ore needs to be increased.
D. Flotation Machine Production Capacity
With the increase of pulp concentration, the capacity of flotation machine (calculated by the amount of dry ore treated) will increase within the rated capacity, and the water and electricity consumption per ton of ore treated will decrease.
E. Flotation time
With the increase of pulp concentration, flotation time will increase, which is beneficial to improve the recovery rate.
In actual production, when determining the ideal pulp concentration, the ore properties and specific flotation conditions must be taken into account and determined by beneficiation test. The general principle is that the denser pulp is often used for flotation of minerals with large flotation ratio and coarse particle size, whereas the thinner pulp is used for flotation of minerals with small flotation ratio and fine particle size. The common flotation concentration is 25-45%, and some can reach more than 50%. Thicker pulp is used in roughing operation, which can ensure high recovery rate and save reagents. The use of thinner concentration in concentrating operation is conducive to improving concentrate grade, generally 15-25%. The concentration of sweeping operation is generally not controlled separately by rough selection. It is usually lower than that of rough selection area and higher than that of fine selection area, mostly 20-40%.

4. Pulp acidity and alkalinity (pH)


When minerals are flotation with different flotation reagents, there exists a critical pH value of "flotation" and "non-flotation". The pH value of pulp often directly or indirectly affects the floatability of minerals. However, the critical pH value will change with the change of flotation conditions. If different collectors are used or their concentration is changed, the critical pH value will change. Under certain floating conditions, there exists a suitable pH value for any mineral. Only at this value can the concentrator obtain better flotation indexes. Therefore, controlling the critical pH value is also one of the important methods to control the flotation process index.
The influence of pulp pH value on flotation process is mainly reflected in the following aspects:

A. Surface Electricity of Minerals
For some oxidized ores and silicate minerals, the slurry pH value will affect their surface electrical properties, and then affect their flotation properties.
B. Floatability of minerals
When collector is used for flotation, the flotability of most minerals will be affected by the pH value of the pulp. When the pulp pH value is lower than the critical pH value, minerals can float up; when the pulp pH value is higher than the critical pH value, minerals can not float up.
C. The Existence of Collectors in Solutions
Under different pH conditions, some collectors will exist in different states.
D. Surface hydroxylation of oxidized ores and silicate minerals
Cations on the surface of oxidized minerals and salts can be hydrolyzed into hydroxyl complexes. Their formation and mass fraction are strictly controlled by the pH value of the pulp, thus affecting the final flotation process index.

5. Pharmaceutical System (Prescription)


In flotation process, the adding system of reagents is often called prescription, which mainly refers to the type, quantity, place, sequence and method of preparation of reagents. Practice has proved that many cases are caused by improper flotation reagent system when flotation process index decreases.

A. Types of medicines
The types of flotation reagents are mainly determined by the results of ore washability study. Different agents play different roles in the flotation process (such as collection, foaming and adjustment). In the production process, even if the same kind of medicines, often will use more than two kinds. For example, when using collector, the effect of mixed medication is better than that of single medication; when selecting gold, yellow medicine and black medicine are used together, the recovery rate of gold is obviously improved.
B. Pharmaceutical dosage
The amount of flotation reagent added is determined by beneficiation test research and practical experience. In production, operators need to adjust the dosage of reagents in time according to the changes of ore properties and other conditions.
The amount of collector is insufficient, and the flotation minerals are not hydrophobic enough, which reduces the recovery rate. Excessive dosage of collector will not increase the recovery of useful minerals, which not only causes waste of reagents, but also improves the floatability of minerals to be inhibited, resulting in the decline of concentrate grade.
The inadequate amount of foaming agent is characterized by less foam and unstable foam layer, which leads to a decrease in recovery. The excessive use of foaming agent increases the pulp viscosity and the flotation foam is too stable, which not only has a negative impact on flotation, but also brings difficulties to concentrate dewatering.
Inadequate dosage of depressants resulted in a decline in concentrate grade. The recovery of concentrate decreases when the depressant is excessive. Therefore, the dosage of inhibitors should be controlled to keep them within the appropriate dosage range.
C. Place and sequence of drug addition
A. Drug Addition Location
Addition site was determined according to dissolution rate and action time of the reagent. The dissolution rate is low and the required action time is long. It can be added to the ball mill, or the distance between the agitation tank and the flotation tank can be increased, or the agitation time can be increased, otherwise it can be added to the agitation tank. If there are gravity separation and mercury mixing operations before flotation, flotation reagents can not be added to grinders, such as gold ore, because floating concentrates will affect the recovery of gold from gravity separation and mercury mixing operations. In addition, some chemicals can "poison" mercury and reduce its ability to collect gold.
B. Order of drug addition
Considering the interaction among various agents, the order of adding agents is generally PH regulator - inhibitor or activator, Collector - foaming agent.
Concentrated addition
Before roughing operation, all medicines are added at one time, which is suitable for medicines that are soluble in water, not easy to be taken away by foam and not easy to fail.
Segmented addition
In the process of separation, two or more additions are made, which is suitable for medicines that are easy to be taken away by foam and fail due to interaction with fine mud or soluble salts.
D. Pharmaceutical preparation
Flotation reagents are classified into solid and liquid reagents. In the flotation process, sometimes the solid reagent is added directly, sometimes the raw liquid is added, sometimes the solid reagent needs to be prepared into a certain concentration of the liquid after adding. The form of the drug is mainly determined by the solubility of the drug, the action time, the dosage of the drug and the operating conditions. Water-soluble agents (such as copper sulfate and xanthate) need to be prepared into 5-20% solution. Drugs slightly soluble in water (black medicine, oleic acid) can be prepared into low concentration solution or directly added to the grinder. Drugs that are insoluble in water can be dissolved by organic solvents and then mixed into low concentration solutions.

6. Pulp temperature


Pulp temperature plays an important role in flotation operation of flotation machine. Heating can accelerate the molecular thermal movement, which has many effects on minerals, such as accelerating the dispersion, dissolution, hydrolysis and decomposition of reagents, increasing the speed of interaction between reagents and mineral surface, promoting the desorption of reagents, and promoting the oxidation of mineral surface.
Two main factors are considered to change the pulp temperature:
A. Some medicines need to be dissolved at a specific temperature and exert their effects.
B. Some minerals have special flotation process requirements.

7. water quality


Flotation process is mainly carried out in water medium, so water quality has a great influence on flotation process and its indicators. Generally, the water used for flotation production mainly includes soft water, hard water, saline water, saturated solution of salt and production backwater. Different production processes have different requirements for water quality. Usually, flotation water should not contain a large amount of suspended substances and substances that react with flotation agents or minerals. In addition, dissolved oxygen content also has a significant impact on flotation process indicators.

8. Flotation time


The residence time of pulp in each operation flotation tank is called operation flotation time. The total flotation time of roughing operation and each sweeping operation is the total flotation time of this process.
The suitable flotation time is determined by beneficiation test. When minerals can be flotation well, the content of flotation minerals is low, the size of flotation feed ore is appropriate, the concentration of pulp is small, and the effect of reagent is strong, the stronger the aeration of flotation machine is, the shorter the flotation time is needed. On the contrary, a longer flotation time is needed.

Increasing flotation time can increase recovery, but concentrate grade will decrease. At the beginning, the recovery rate increased obviously, but with the prolongation of flotation time, the increase rate decreased gradually until a fixed value.


Flotation process is a common mineral processing method in concentrator production. Its process will directly affect the final technical and economic indicators, and its importance can be imagined. In the actual production process, we must pay attention to every detail of flotation process, and determine the process parameters according to the results of scientific beneficiation test report, so as to obtain ideal benefits.

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