Concrete requirements for stone powder content in sand

Stone powder refers to particles less than 75μm in artificial sand and mixed sand. Most of the stone powder in artificial sand is fine particles of broken parent rock. Unlike mud in natural sand, their role in concrete is also very different. On the one hand, high stone powder content increases the specific surface area of sand and increases water consumption; on the other hand, the ball effect produced by fine spherical particles will improve the workability of concrete. Therefore, stone powder in artificial sand cannot be regarded as a harmful substance.

The comprehensive impact of stone powder content on artificial sand has been proved by decades of experiments: Guizhou Province began to study the use of artificial sand in the 1970s. When the stone powder content in artificial sand is 0-30%, it has little effect on the performance of concrete, has no effect on the compressive and tensile strength of medium and low-grade concrete, and has little effect on the strength of C50 grade concrete. The shrinkage is close to that of river sand. The experimental research of the Railway Science Institute also proved that the mechanical properties of concrete prepared with artificial sand are better than those of river sand concrete (under the condition that the cement dosage and the consistency of the concrete mixture are equal).

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Chromite purification processing method

At present, chromium ores with industrial value are generally chromium-magnesia spinel or chromium-iron spinel minerals, which contain a large amount of chromium oxide, with a content of about 18% to 62%, and generally also contain metals such as aluminum and nickel. Its characteristics make the chromium ore beneficiation process present a rich and diverse state. Due to the properties of chromium, chromium ore beneficiation processes include gravity separation, magnetic separation, flotation, combined beneficiation, chemical beneficiation, etc. Commonly used in industry are single gravity separation, single magnetic separation, and gravity-magnetic combined beneficiation processes. In terms of equipment selection, shakers and jigs are mostly used in the gravity separation stage, while the equipment selection in the magnetic separation stage is determined based on the magnetism of the ore.

The classifications of quartz sand

1. Ordinary quartz sand: The surface of ordinary quartz sand seems to have a layer of yellow skin, and some have large particles and strong fire resistance. It is a kind of quartz sand processed by the manufacturer after using natural quartz ore in the production process, such as washing and drying. No impurities can be seen in the quartz sand through the second water treatment filtration. It is the best choice for chemical water treatment. It can block the sundries suspended in the water and maintain the quality and beauty of the water. 2. Refined quartz sand: Refined quartz sand is a mineral made by the manufacturer after carefully selected quartz stone. According to different requirements of users, the range used is also different. But generally the main use of refined quartz sand is in glass products, because refined quartz sand is refractory and precision casting, especially suitable for fireproof glass materials.

Slove method of the clogging of trommel screen sieve

The drum screen is a simple screening device. The trommel screen is easy to close and collect dust, the maintenance is small, the maintenance is simple, and the service life is long. It is a device frequently used in refractory materials, coal, river sand classification, and sandstone classification. The advantage of the trommel screen is that the structure is not complicated so that the device can be quickly operated, and when the trommel has problems, people can easily solve it. But what should I do when the screen of the trommel screen is blocked? The following screen will introduce several ways to solve the phenomenon of blocking the net. The trommel screen sometimes adopts a mechanism added to the fixed frame, and then the mechanism rotates to drive the belt mounted on the belt to continuously smear the surface of the sieve hole, thereby sucking out the raw material particles blocked in the sieve hole. One of the disadvantages in practice is that it produces a lot ...

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