How to remove aluminum impurity in high purity quartz sand?

In this paper, a method of deeply removing aluminum impurity from high purity quartz sand is shared.

In sand washing and silica sand processing plant, Quartz sand contains many kinds of impurities, of which iron and aluminum are the most difficult to remove, so the content is high. Among these two impurities, especially aluminum is the most difficult to remove, so the content is the highest. In most cases, the impurity aluminum content is several times to more than 100 times the impurity iron content. It is generally believed that this is due to the special structure of silica: Aluminum exists in quartz lattice in the form of mutual inlay, which greatly increases the difficulty of separation. In view of this, at present, for further deep aluminum removal of industrial quartz sand, the extreme method of strong acid, strong alkali and high temperature is mostly used to effectively destroy the lattice structure of quartz and remove impurities therein.


Sinonine provides a method that not only does not cause the loss of the main target mineral quartz sand, but also can effectively remove the impurity aluminum in quartz sand in a relatively fast time, so that it can reach the world recognized aluminum content level of high-quality quartz sand, while greatly reducing the harm to the environment.
The specific methods are as follows:

Aluminum in quartz sand was leached by mixing 0.5% oxalic acid and 1.0% hydrochloric acid at a weight ratio of 0.5:99.5. Mixed acid: the weight ratio of quartz sand is 1:1, and the removal rate of aluminum in quartz sand can be up to 53% after ultrasonic stirring for at least 1 hour. In addition, the ultrasonic frequency is 25-40khz and the power is 360W outside the reactor.


The function of oxalic acid is mainly to accelerate the initial speed of impurity removal, while the function of ultrasonic is mainly to strengthen the mass and momentum transfer in the leaching process at the molecular level, to accelerate the surface renewal of reaction layer between quartz sand particles and solution, and to make the impurity aluminum protons in quartz sand in an unstable state under the alternating power and to prevent new association or combination, so as to facilitate the transformation from quartz sand to quartz sand split it out.


After the test, the quartz sand with SiO2 content as high as 99.87% and impurity aluminum content as 37.1ppm was treated. At the bottom of the reactor, the mixture of 1.0% hydrochloric acid and 0.5% oxalic acid is mixed at a temperature of 80 ℃, the ultrasonic frequency is 40KHz, the power is 360W, and the weight ratio is 99.5/0.5. Quartz sand of equal weight is added to the mixture. The leaching rate reaches 53% after 1 hour of reaction. After leaching, the content of aluminum in quartz sand is 17.4ppm, which is higher than 22.7ppm of unimin.