October 14, 2019

How to produce high purity quartz sand by calcination?

This paper introduces a purification method of quartz sand, focusing on the calcination and purification of high-purity quartz sand.

In the feild of silica sand processing plant, quartz needs to be melted at high temperature in the process of making quartz sand, and a certain amount of quartz sand is poured into the smelting furnace for burning. However, because the quartz sand used is not classified, the purity of the calcined quartz sand is not high, and the utilization rate of raw materials is wasted. In the process of calcining, the furnace body keeps a posture, and the liquid quartz sand in the furnace is not uniformly heated, so raw materials will be wasted. Increased usage and other costs. Sinonine provides a calcination method for high purity quartz sand. The quality of quartz sand prepared by this calcination method can reduce the overall manufacturing cost, and the forging method can meet the mass production, thus improving the utilization of raw materials, reducing the production cycle and production costs.

Quartz Sand by Calcination

Preparation of High Purity Quartz Sand by Calcination
 
The calcination method of high purity quartz sand includes the following steps:
Step 1: Transfer quartz sand through belt conveyor to vibrating leaky belt for running water flushing.

Step 2: Place quartz sand in pickling equipment for pickling, add Aqua regia, the weight percentage of aqua regia and quartz sand is 1% - 8%, mixing time is 1 - 2 hours, soaking time is 1 - 3 hours, and then release aqua regia on the surface of quartz sand.

Step 3: Place quartz sand in the baking room for baking. The baking time is 2-4 hours and the temperature is 300-400 centigrade.

Step 4: The quartz sand is classified into ordinary quartz sand with silica content of 90% - 99%, ordinary quartz sand with silica content of 89% - 98%, and low-grade quartz sand with silica content of 88% - 97%.

Step 5: A graphite electrode rod with a diameter of 10 cm-13 cm and a length of 270 cm-290 cm is inserted into the smelting furnace.

Step 6: Tightly wrap the ordinary quartz sand with silica content of 90%-99% in 5-6 tons around the graphite rod into the smelting furnace, tightly wrap the ordinary quartz sand with silica content of 89%-98% in 1-2 tons around the ordinary quartz sand into the smelting furnace, tightly wrap the low-grade quartz sand with silica content of 88%-97% in 4-5 tons around the ordinary quartz sand into the smelting furnace. In the process, high purity quartz sand blank is calcined.

Step 7: Calcinate the billet at 1600 - 2000 centigrade for 10 - 13 hours.

Step 8: After calcining the billet at high temperature for 0.5-1 hour, the vertical furnace body is turned over at a certain angle, and the liquid quartz sand is heated evenly.

Step 9: The calcined quartz billet is cooled naturally for 1-2 hours. After the liquid in the calciner is cooled to crystalline form, the quartz billet is taken out and the residual temperature emitted from the quartz billet is collected.

Step 10: The cooled quartz material is crushed to get 20-200 mesh quartz sand, and then classified. The silica content is 99.9-99.99% and the ferric oxide content is less than or equal to 0.001% for high-purity quartz sand. Then the high-purity quartz sand is ground into 800-500 mesh quartz powder.
 
In step 1, the vibration leaky belt is densely filled with holes of 0.5-1.5 cm in diameter.
 
In step 5, the graphite electrode rod is installed in the middle of quartz sand, and the optimum length and diameter of graphite shock rod are 280 cm and 12 cm respectively.
 
In the seventh step, the calcined billet gradually melts into liquid form during high temperature calcination, and the optimum calcination time is 12 hours.
 
In step 8, the angle of furnace body turnover is 90-180 degrees. Furnace body turnover is divided into three stages. Furnace body turnover occurs every half hour in the first four hours, once every twenty minutes in the middle four hours, and once every fifteen minutes in the last four hours. The furnace body is in a vertical state in the first half hour. After calcining at high temperature for half an hour, the quartz sand in the furnace is in liquid form, which makes the furnace body turn over 90 degrees and makes the liquid quartz sand in the furnace body heated uniformly. When the furnace body is turned over for the second time, the optimum angle is 180 degrees. After that, the optimum angle for each turn of the furnace body is 180 degrees. The optimum temperature for calcining billet is 1700 centigrade.
 
In step 9, the calcined quartz blank is collected and transferred to the baking room for baking the acid-washed quartz sand.
 
Process flow of calcination to prepare high purity quartz sand

The preparation process of high purity quartz sand consists of four parts: washing process, pickling process, drying process and calcination process.
 
Taking each batch of 10 tons quartz sand as an example, the detailed production process is as follows:
 
10 tons of quartz sand is conveyed to the vibrating leaky belt by belt conveyor to wash with running water and then put into the container for pickling. 1.25 tons of aqua regia is added to the container, and the aqua regia on the surface of quartz sand is stirred for 2 hours during 3 hours of soaking, then the aqua regia on the surface of quartz sand is released; quartz sand is baked in the baking room for 3 hours at 350 centigrade; a graphite electrode rod with a diameter of 12 cm and a length of 280 cm is installed. Insert in the smelting furnace; wrap 6 tons of ordinary quartz sand with silica content in 90%-99% tightly around the graphite rod into the smelting furnace; wrap 1 ton of ordinary quartz sand with silica content in 89%-98% tightly around the ordinary quartz sand into the smelting furnace; wrap 3 tons of low-grade quartz sand with silica content in 88%-97% tightly around the ordinary quartz sand into the smelting furnace. The calcined billet is calcined to high purity quartz sand billet; the calcined billet is calcined at 1750 centigrade for 12 hours; after calcining the billet at high temperature for 1 hour, the vertical furnace body is turned over at a certain angle to make the liquid quartz sand heated uniformly; the calcined quartz billet is naturally cooled for 2 hours, and the liquid in the calciner is cooled to crystalline form, and then the quartz billet is taken out. The residual temperature emitted from quartz billet was collected, and 200 meshes of quartz sand were obtained by crushing the cooled quartz material and grading. The content of silica was 99.99% and the content of ferric oxide was less than or equal to 0.001% for high purity quartz sand, and finally the high purity quartz sand was ground into 500 meshes of quartz powder.
Quartz Sand powder

CONCLUSION: Quartz sand is purified by calcination. Furnace experience can be turned over automatically in different time periods, which makes quartz sand heated uniformly in the furnace body, greatly improves the quality and efficiency of quartz sand purification, and reduces the cost of production. At the same time, the utilization rate of raw materials has been greatly improved, and the utilization rate of quartz sand is as high as 80%, which saves the cost.

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