Nov. 27, 2024
The purification of quartz sand is very difficult, mainly because it contains some impurity minerals, some of which containing iron elements, such as goethite, hematite, limonite, ilmenite, pyrrhotite, tourmaline, amphibole, biotite and so on.
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These impurities greatly reduced the use-value of quartz sand, so the removal of iron from quartz sand is very important. The following introduces 7 methods and equipment for removing iron from quartz sand.
Quartz sand
Gravity separation can usually be used effectively for the entire particle size range of quartz sand. When the iron in quartz sand is mainly in the form of heavy minerals (relative density > 2.9), gravity selection should be considered firstly. But gravity separation is difficult for mixed particles, flaky particles, light mineral particles and medium-density minerals.
Criteria for gravity separation: E = (heavy mineral density-medium density)/(light mineral density-medium density).
When E > 2.5, gravity separation can be easily adopted;
when it decreases, the efficiency of gravity separation decreases;
when it < 1.25, gravity beneficiation will be not suitable. The commonly used equipment is the spiral chute and shaking table.
Spiral chute gravity separation can be used when the material contains a particularly small amount of heavy mineral impurities (such as zircon). The greater the specific gravity difference of minerals, the higher the degree of separation.
Fote spiral chute
When the spiral chute is used for beneficiation, the quartz mortar can be divided into three parts: granular heavy mineral area, granular quartz sand area, flaky and light quartz sand area. In this way, not only the heavy minerals in quartz sand can be removed by the spiral chute, but the mica minerals can also be removed partially.
Advantages of spiral chute:
1
Reasonable structure, simple installation and small floor space.2
It is made of chlorinated plastic with great advantages of lightweight, moisture-proof and corrosion-resistant.3
The spiral chute is highly adaptable. The feeding capacity, the concentration of ore, the particle size and grade of the original quartz sand have almost no influence on the beneficiation results.4
Large processing capacity, high work efficiency, low cost and energy saving.5
Good processing effect. It is reflected in stable beneficiation, clear separation, large processing capacity, high efficiency and high enrichment ratio of beneficiation.6
The spiral chute itself has no moving parts, no power consumption, and almost no noise. In addition to the high quality of the quartz sand and no washing water, it has achieved the dual effect of environmental protection and energy-saving.The shaking table is a kind of practical gravity separation equipment with high-cost performance. The content of mica in quartz sand can be effectively reduced by the shaking table.
Characteristics of the shaking table
Characteristics of the shaking table:
Quartz, the main mineral in quartz sand, is a diamagnetic substance that cannot be magnetized in a magnetic field. The iron-containing impurity minerals in quartz sand, such as hematite, limonite, magnetite, goethite, etc., are mostly magnetic.
The magnetic separation process is to take advantage of such difference in nature to remove these iron-containing impurities from quartz sand.
Magnetic separation method
Characteristics of magnetic separation method:
1
It can remove weakly magnetic impurity minerals such as hematite, limonite and biotite including conjoined particles to the maximum extent.2
The more times of magnetic separation, the finer the grain size of quartz sand and the better the iron removal effect.1
High concentrate recovery rate. The quartz sand magnetic separator has strong magnetic separation ability, good separation effect, and no concentrate loss.2
A permanent magnetic system with no need for continuous excitation. Permanent magnetic system is adopted in the quartz sand magnetic separator, so the magnetism is not easy to disappear, saving cost.3
Convenient production operation. The quartz sand magnetic separator is integrated with higher electrical control technology to improve work efficiency and reduce the labor intensity of operators.4
High grade of concentrate. The beneficiated quartz sand concentrate has a high grade, and high purity with no impurities, which greatly improves resource utilization.5
Durable. The magnetic drum is wrapped with double-layer drum leathers, which can better protect the internal structure and save maintenance costs while ensuring the magnetic force.The quartz sand flotation method mainly removes iron-containing mineral impurities such as mica, feldspar, garnet and amphibole. A three-stage flotation process is used to remove iron-containing argillaceous, mica and feldspar minerals from quartz sand respectively.
The quartz sand flotation method
Advantages of the flotation method:
The removal of iron from minerals by flotation can achieve better results than other methods. It can not only remove iron minerals, but also particles with iron films and clay minerals.
Therefore, many quartz sand concentrators adopt flotation methods.
1
The quartz sand flotation machine adopts the automatic control system of unmanned operation, which simplifies the operation of the equipment.2
If you want to learn more, please visit our website quartz sand beneficiation equipment.
Simple structure with no need of fans and ventilation ducts. Its unit volume handling capacity is 2~3 times that of conventional flotation machines.3
The important parts and wearing parts of the quartz sand flotation machine are protected by wear-resistant devices, so the consumption of each part in the flotation is less and the maintenance cost is low.4
In the flotation process, the equipment can keep the foam area stable with a certain thickness, and make inclusions gangue of the quartz sand off, resulting in "secondary enrichment", which is beneficial to improve the precision of the finished product.If the finished quartz sand is reddish, and the iron and titanium content does not meet the product quality requirements, the acid leaching method can be used. Wash the quartz sand with water to remove powder and impurities, then carry out acid leaching before drying it.
Quartz sand acid leaching method (chemical treatment) has good iron removal effect, but the cost is higher, the technical requirements are stricter, and it is harmful to the environment. However, in order to obtain higher purity quartz sand, this chemical method will inevitably be used in the future.
Stirring and scrubbing are accomplished by friction between particles caused by violent agitation of the blades. However, since iron oxide films are thin and strong, this method is unlikely to remove them. If necessary, chemical reagents can be added.
Stirring and scrubbing
The process has the following characteristics:
1
The product is of good quality and can meet the quality requirements of high-quality silica sand.2
Large output, low cost and simple operation. Now some small-scale production and processing enterprises use this method to remove iron.Ultrasonic iron removal is mainly to remove the secondary iron film on the surface of the particles. When treated with ultrasonic technology for 10 min, its iron removal rate can generally reach 46% to 70%. In order to improve the effect of ultrasonic cleaning, a small number of reagents (such as sodium carbonate) and surfactants (such as water glass) can be added.
Ultrasonic iron removal is currently relatively expensive for the beneficiation of quartz sand, and it is still difficult to apply in large-scale concentrators, but for those who require high purity, low production is possible.
Microbial leaching of thin-film iron or immersion iron on the surface of quartz sand particles is a new technology for iron removal, which is currently in the research stage of laboratory and small-scale experiments.
The microbial Aspergillus niger leaching has a good effect on iron removal. The removal rate of Fe2O3 is up to 88.8%, and the grade of Fe2O3 in quartz sand is as low as 0.008%.
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Quartz sand is a common and widely used non-metallic raw material. Due to the needs of its application field, the requirements for the removal of impurities in quartz sand are relatively high in the process of quartz sand mineral beneficiation. In this article, we will take you through the separation process of quartz sand and its common gangue minerals. Common gangue minerals in quartz sand mineral include metallic minerals such as hematite, magnetite, limonite, and ilmenite, as well as non-metallic minerals mainly composed of feldspar. Below we will divide it into two parts for explanation.
Use the table of contents below to navigate through the guide:01
Quartz sand mineral separates from metallic minerals02
Separation of quartz sand and non-metallic minerals01
Quartz sand mineral separates from metallic mineralsThe metal minerals in quartz sand mineral are mainly iron-containing minerals, which exist in the following forms in quartz sand:
1. Exist in clay or kaolinized feldspar.
2. Adhere to the surface of quartz particles to form iron hydroxide film.
3. Exist in heavy mineral impurities such as ilmenite.
4. Exists in quartz particles in the form of dissemination or infiltration.
5. Exist in mica, hornblende and other ore particles.
Since the form of iron impurities is relatively complex, its separation process is also relatively diverse, mainly including the following five types:
The scrubbing method uses mechanical force and mutual grinding and peeling of mineral particles to remove thin film iron and adhesive impurities on the surface of quartz sand, and can also remove some iron minerals in clay feldspar. In this method, the factors that have a relatively large impact on the scrubbing effect include the structural characteristics and configuration form of the scrubbing machine itself, scrubbing time, scrubbing concentration, etc. The choice of scrubbing equipment should be determined after testing according to the nature of the quartz placer. The concentration of scrubbing is generally controlled at 50%~60%, and the scrubbing time is subject to the preliminary product quality requirements, which should be determined according to the test.
Magnetic separation is mainly used to remove magnetic minerals such as hematite, limonite, magnetite and biotite. When the iron impurities in the quartz sand are low, a wet strong magnetic separator is generally used for separation. The more important factor is the fineness of the selected minerals. Generally, the finer the ore particles of the quartz sand, the better the effect of separating iron impurities.
Gravity separation can remove heavy minerals in quartz sand, mainly ilmenite, whose density is greater than 2.9g/cm3, and spiral chute is often used as quartz sand gravity separation equipment.
The flotation separation method can be divided into two processes: separate flotation of iron and mica and joint flotation of iron and mica. The chemical systems used in these two methods are different, mainly using petroleum sulfonate and pine oil with flotation iron, and sulfuric acid as the slurry regulator.
In addition to the above three conventional beneficiation methods, microbial leaching is also a method that can remove thin film iron on the quartz surface. Microorganisms such as Aspergillus niger and Penicillium are mainly used to soak it, but this technology has not been applied to large-scale industrial production.
02
Separation of quartz sand and non-metallic mineralsQuartz sand is similar to non-metallic minerals such as feldspar and clay, so it is difficult to separate feldspar from quartz sand. When removing feldspar impurities, it is generally treated by water washing and desliming, flotation, and acid leaching.
For quartz sand containing a large amount of clay minerals, water washing and desliming is an effective way to remove clay, and it is often used as a preparation for impurity removal and purification before quartz sand is selected.
The flotation process of quartz sand can be divided into flotation with fluorine and flotation without fluorine. Fluorine flotation is another method of selecting cationic collectors and hydrofluoric acid activators. Fluorine-free flotation uses sulfuric acid or hydrochloric acid as the activator of feldspar, and then uses the corresponding collector to separate feldspar. Under the same conditions, the flotation effect of using hydrochloric acid as an activator is better than that of using sulfuric acid as an activator.
Because quartz is stable in nature and insoluble in other acids except hydrofluoric acid, acid leaching is an effective method for removing non-metallic minerals in quartz sand. Commonly used acids include sulfuric acid, hydrochloric acid, nitric acid, etc. The acid concentration, dosage, acid leaching time, temperature, slurry stirring and other factors can affect the acid leaching effect.
Above we have introduced the separation process of quartz sand mineral and common gangue minerals. It should be noted that the quartz sand produced in different mining areas has different mineral components. In actual production, a scientific and reasonable mineral processing process should be adopted according to the mineral processing test, and an appropriate process flow should be adopted to obtain good economic benefits.
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