Iron impurities in quartz sand mainly white mica, pyrite and Other forms of iron oxide (Fig. 1) is present, the presence of iron impurity greatly reduces the value of quartz sand, affect product quality.
Figure 1 Quartz rock backscattered electron image
(a)-(c) are quartzite samples; (d) are iron impurity particles magnetically selected from wet quartz sand
In actual production, the removal of iron from quartz sand requires the raw material to be washed with water, and then mechanical scrubbing, magnetic separation, flotation, ultrasonic cleaning, acid leaching and other processes to remove iron from quartz sand and improve the use of quartz sand. value. So how many quartz sands are most suitable for beneficiation and purification?
Taking Fengyang quartz sand as an example, the above figure shows that the content of Fe2O3 in -60+180 mesh quartz sand is the lowest, the average value is 0.0075%, and the SiO2 content is the highest, with the average value being 99.28%. Mainly due to the fact that most of the iron-containing minerals in the -60+180 mesh quartz sand have been separated during the grinding process, so the iron content is low.
The content of Fe2O3 in quartz sand with particle size greater than 60 mesh increases with the increase of particle size, and the content of SiO2 decreases with the increase of particle size. The content of Fe2O3 in +50 mesh quartz sand is 0.0522% and the lowest in SiO2 is 98.32%. This is because the size of the quartz sand with a particle size of +50 mesh is larger than the size of the quartz particles, so that a plurality of quartz particles are contained inside the single quartz sand particles, and the iron-containing mineral inclusions existing between the quartz particles are not separated, thereby Resulting in an increase in the iron content of the +50 mesh quartz sand.
The content of Fe2O3 in quartz sand with particle size less than 180 mesh increases with the decrease of particle size, and the content of SiO2 decreases with the decrease of particle size. The content of iron in -300 mesh quartz sand is up to 0.0587% (3 times that of quartz fiber sample of -200+300 mesh). The SiO2 content is at least 98.81%. This is mainly because the size of the iron-bearing minerals in the quartz stone is generally less than 0.01 mm. When the quartz stone is ground to 50 μm, most of the iron-containing minerals present in the impurity phase inside the quartz fall off and enter the -300. In the quartz sand, the iron content in the -300 mesh quartz sand is high.
Quartz sand magnetic separation purification process
The above data shows that the smaller the particle size, the higher the impurity content, which is also the reason why the quartz sand should be delimed in stages before beneficiation and purification. In addition, the variation of iron content in quartz sand with particle size is: when the particle size of quartz sand is larger than 60 mesh, the iron content increases with the increase of particle size, and when the particle size is less than 180 mesh, the iron content increases with the decrease of particle size.
Therefore, in the quartz sand beneficiation purification process, the raw material should first be water-eluted, and then the quartz sand particle size should be controlled between -60+180 mesh to effectively improve the quality of the product and reduce the content of iron impurities in the quartz sand. For quartz sand with a particle size of more than 60 mesh and a particle size of less than 180 mesh, the magnetic separation can be enhanced, which can effectively reduce the content of iron impurities in the quartz sand.
The current prospects of the quartz sand market make the development of quartz sand deep processing and high purification technology extremely urgent. In this regard, China Powder Network is scheduled to hold the “2017 Quartz Sand Fine Processing and Application Technology Exchange Conference†at the Fengyang International Hotel in Anhui Province on December 12-13, 2017 in the Quartz Sand Industry Cluster. The conference aims to provide local and domestic quartz sand industry people with a communication platform for quartz sand purification and fine processing technology, strengthen industry information exchange, and provide quality solutions for enterprise product transformation.
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