How to distinguish coarse sand, medium sand, and fine sand? What equipment is used to produce high-quality machine sand?

In the current situation, with the vigorous promotion of infrastructure construction, the demand for sand and gravel aggregates is also increasing day by day. Many places have issued documents prohibiting sand mining activities in river channels, mainly because the speed of sand mining has exceeded its natural recovery rate. Therefore, many departments are vigorously promoting mechanism sand and providing policy support to solve the problem of difficult sand use. However, how to distinguish coarse sand, medium sand, and fine sand? What equipment is used to produce high-quality machine sand? Here is a detailed explanation for everyone.

1、 How to distinguish coarse sand, medium sand, and fine sand?

The fineness of sand refers to the average fineness of sand particles of different sizes mixed together. Generally, coarse sand, medium sand, and fine sand are distinguished by fineness modulus and particle size. Generally, the larger the fineness modulus, the coarser the sand, while the smaller the fineness modulus, the finer the sand.

1. Coarse sand: The fineness modulus is 3.7-3.1, and the content of particles with a particle size greater than 0.5mm exceeds 50% of the total weight. The average particle size is sand and gravel with a particle size greater than 0.5mm.

2. Medium sand: The fineness modulus is 3.0-2.3, and the mass of particles with a particle size greater than 0.35mm exceeds 50% of the total weight, with an average particle size of 0.5-0.35mm sand and gravel.

3. Fine sand: The fineness modulus is 2.2-1.6, and particles with a particle size greater than 0.25mm exceed 85% of the total weight, with an average particle size of 0.35mm-0.25mm sand and gravel.

Extended information: Main uses of machine made sand

Coarse sand: mainly used for concrete in beams, slabs, columns, foundations, and floors.

Medium sand: used for concrete mixing, masonry, plastering mortar, plastering of internal and external walls, ceilings, and leveling of floors (roofs).

Fine sand: Mortar used for masonry construction. When using coarse or medium sand to make concrete or plaster mortar, if it is too coarse to form grout, a certain amount of fine sand should be added appropriately.

2、 What effect does the thickness of sand have on concrete?

Machine made sand is widely used in concrete, and builders have higher requirements for concrete. Of course, the thickness of machine made sand has a significant impact on concrete, and its workability, cement dosage, pumpability, concrete crack resistance, and even concrete strength are all related to the gradation of sand and gravel.

1. The coarser the sand, the more unfavorable it is for the preparation of pumped concrete. Therefore, it is necessary to ensure a certain amount of fine particle content. At the same time, to ensure working performance, it is necessary to increase the sand rate, which will enhance the strength of the concrete.

2. The finer the sand, the less it can form a good gradation, resulting in discontinuous concrete gradation and reduced concrete strength. It also requires an increase in cement dosage, which leads to an increase in hydration heat, which is not conducive to conservation and crack resistance.

3. The poor grading of sand and gravel may cause sand damage at the edges and corners of concrete components, affecting the appearance. Generally, medium coarse sand is used for engineering sand.

3、 What equipment is used to produce high-quality machine sand?

Machine made sand refers to particles with a particle size less than 4.75mm that are mechanically crushed and screened after soil removal treatment. What equipment is required? How can we produce high-quality machine made sand? It still depends on the demand for raw materials and production capacity, as well as whether the particle size and shape of the finished product meet the standards. There are experienced technical engineers here, who will also customize the production process of machine sand for each customer based on the company's environment, infrastructure settings, budget, and other conditions.

1. How can we produce high-quality machine made sand?

① At present, there are nearly 200 types of sand making raw materials on the market, and weathered soft rocks are not selected. The Mohs hardness is around 3-8 levels, and ideal machine made sand raw materials include limestone, granite, pebbles, etc;

② Choose the production process and process of "more breaking and less grinding" to allow the material to break according to its own texture surface, resulting in a smooth and angular particle shape, as follows:

Raw materials → Vibration feeder → Jaw crusher → Medium crushing (impact crusher/cone crusher) → Vibration screen → Sand making machine → Vibration screen → Sand washing machine → Fine sand;

③ Reasonably utilize equipment such as sand washing, screening, and powder selection, and control the particle size of the finished product to not exceed 4.75mm, the mud content to be less than 5%, the stone powder content to be less than 5.0%, and the mud lump content to be less than 2.0%;

2. Introduction to Production Mechanism Sand Equipment

Jaw crusher: The raw materials are sent to the vibrating feeder through a dump truck, and are uniformly and continuously fed to the jaw crusher for coarse crushing. The cavity is deep and there is no dead zone, so there is no need to worry about material blockage. The crushing can start at the upper part of the crushing cavity, and the stroke is larger and the crushing ratio is larger at the lower part of the crushing cavity. The wedge adjusts the discharge port, and the finished product particle size is adjusted within a range of 10-350mm, with uniform particle size, which is helpful for the second stage crushing treatment.

Counter crushing/cone crushing: After rough crushing, the raw materials are transported by a belt conveyor to a counter crushing machine (soft materials such as limestone) or a cone crusher (hard materials such as river pebbles and granite) for secondary processing. The finished product has a particle size of 3-60mm, and after reasonable screening by a vibrating screen, unqualified stones or sand that do not meet the requirements are returned to the counter crushing machine for re crushing.

Sand making machine: After crushing treatment, the material is evenly sent back to the sand making machine. It adopts the working method of stone and stone iron, and the deep cavity impeller design, which increases the throughput of the entire machine. The processed machine sand is 0.25-0.5mm, with good particle shape, fewer needle shaped particles, and reasonable grading.

Screening and sand washing: The material enters the vibrating screen through a conveyor, with a 4-layer screen and three types of sand sizes that can be screened at once. The sand washing machine separates the soil, impurities, and sand to achieve purification and control the content of stone powder.

4、 How much is the cost of a set of machine made sand equipment?

The prices of machine made sand equipment vary in the market due to the variety of processing plans and the different production processes applicable to different production needs. Therefore, the prices also vary. A production line that is more suitable for the actual situation of users can not only save investment and operating costs, but also continuously produce to achieve high profits for users. It is recommended to compare products with three suppliers and pay attention to after-sales service. If after-sales service is not timely, This will result in an increase in subsequent production costs.