Autoclaved Bricks from Tungsten Tailings

In China, a large amount of tungsten tailings and tungsten waste rock after hand picking has been produced in the mining and processing of tungsten ore. And they are generally dumped into and stored in the tailings ponds. For a long period, most mining businesses are committed to production of tungsten ore, the reclamation of tailings have rarely been noticed.

Tungsten tailings itself is a kind of silicate-rich mineral. It is mainly composed of SiO2, Al2O3, CaO, etc. Thus, a reclamation method of tungsten tailings, waste rocks after hand picking, and calcium carbide slag as the main raw material for the production of non-sintered bricks has been introduced. The autoclaved bricks are prepared by pressing and autoclaving process. This reclamation does not only eliminate the environmental pollutions caused by tungsten tailings ponds, but also can be used as a substitute for clay sintered solid bricks.

The preparation process is as follows:

1) Use a hydrocyclone to sift and classify the tungsten tailings, remove the fine-grained grade materials, and use the coarse-grained grade materials as the brick-making raw materials, make sure the mud content <5%, the particle size is -0.074 mm< 8%, +0.16mm>36%, +1.25mm<2%.

2) The waste rocks after hand picking are broken to a size of 3-10 mm with a jaw crusher, and then the particles are washed until the content of the stone powder is <3%;

3) The calcium carbide slag is dried and placed in a ball mill for grinding, grinding to -0.074mm content of 90%.

4) Add the materials prepared in steps 1, 2, and 3 to the water with a total mass of 6-11% of the dry material, and then stir for 10 minutes through a strong mixer, let the materials mix and let stand for 2 hours, then stir the water twice. The water addition amount is 2%, the second stirring time is 5 min, and the mixed mixture is press-formed at a molding pressure of 20 to 30 KN. Then, the formed brick is allowed to stand, and then sent to an autoclave for autoclaving, and is cured in steam at a pressure of 1.0 to 1.3 MPa and a temperature of 170 to 190 ° C for 6 to 8 hours, and then cooled and taken out.

This reclamation method uses tungsten tailings, waste rock after hand picking, and calcium carbide slag to produce autoclaved bricks. The production of raw materials is 100% solid waste, and the production process is simple and convenient. The main purpose is to provide a reasonable utilization route for the tailings and waste rocks after mining and processing of tungsten ore.

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