LDHB MachinesLDHB Machines
The geological structure and composition of limestone mines are relatively complex. Usually, there is a layer of soil on the surface, and there are many mud cracks and water cracks of varying widths and extremely irregular trends inside, as well as yellow gangue and weak layers. The mining process is full of many inconveniences. certainty.
The sand and gravel aggregates produced by limestone mines have a distinctive feature: the mud content fluctuates greatly and easily exceeds the standard. The effect of mud content on the performance of ready-mixed concrete is decisive, it will significantly accelerate the slump loss of concrete, increase the pumping pressure, increase the risk of cracking, etc. Therefore, the mud content is the focus of the quality control of sand and gravel aggregates.
Standard of the sand production line
The process design, production, testing and management of the sand and gravel production line should be rationally planned, in order to produce sand and gravel products with mud content up to the standard, and to save production costs and reduce ore resource waste as much as possible.
Process Design
In order to achieve a good desilting effect, the process design of the production line should adopt “double desilting”, that is, the small particles should be screened out before the first crushing, and the size of the screen should be controlled at 20-40mm. If the size is too small, the desilting effect is not good; If the size is too large, a large amount of stone will be screened, which is not conducive to cost control. The remaining stone is crushed and sieved again, and the particles below 4-5mm are screened out. In this way, the mud content of the remaining stone after two screenings is completely controllable, and the mud content of the machine-made sand and crushed stone produced by subsequent crushing will also be absolutely controllable.
The fineness modulus of the 4-5mm particles mentioned above is usually 2.8-3.5. If the MB value is properly controlled, it can be used as an unshaped machine-made sand. It should be noted that the output of this unshaped machine-made sand (referred to as primary sand) is not low, accounting for 15-25% of the total sand and gravel output. If primary sand can be used in concrete normally, it can not only reduce resource waste, but also Will increase the added value of the product.
Considering that the quality of the primary sand meets the technical requirements for the use of concrete raw materials, a powder separator should be installed on the finished product belt of the primary sand. MB value.