Natural stone ground grinding technology

The promotion and application of diamond tools in the stone industry not only improves the quality of stone products, but also reduces the price of stone products. Therefore, the market of stone products has prospered for more than 20 years, especially the stone veneer for diamond grinding and polishing. Favored by the construction industry. Marble and granite floor tiles are the bulk of polished stone veneers. Many large buildings such as government and large corporate office buildings, star hotels, convention centers, airport terminals, theater halls, supermarkets, and banking halls. Marble or granite floor tiles are used to lay the ground. Therefore, it looks luxurious, bright, elegant, solemn, and spelled into a pattern.
Although marble and granite floors have a certain degree of wear resistance, after years of use, especially in places where people have large circulation, they are always tarnished by wear or scratches, and some occasions are subject to dirt. Pollution left a stain. In order to restore its original appearance, refurbishment measures are taken to make it necessary.
The grinding and polishing of marble floors is now illustrated by examples. The Great Hall of the People, located on the west side of Tiananmen Square, was built in September 1959. The floor of the Great Hall of the People is paved with the world-famous Yunnan marble. After 40 years of use in 1999, the marble floor has been worn and scratched in places where people are frequent, and needs to be refurbished to restore brilliance. . The refurbishment project was carried out by a Swedish company with a total area of ​​5,000 m2, using diamond grinding and polishing technology, equipped with two HTC800E ground grinders, and then polished with a single head polishing machine. The company has a lot to learn about the grinding and polishing technology of marble floors.
The HTC800E ground grinder has a grinding disc diameter of 800mm and is equipped with three grinding heads with a diameter of 270mm. Each grinding head is equipped with several diamond grinding blocks. The three grinding heads rotate in the same direction, while the grinding discs rotate in opposite directions. The choice of the grinding block is critical and is chosen according to the texture of the ground stone being ground. The floor of the Great Hall of the People was laid with marble from Yunnan. The company decided to use a metal-bonded synthetic diamond grinding head for initial grinding after careful testing. The grinding head contains 60/80 mesh Premadia synthetic diamond. In order to remove the wear scar left in the initial grinding stage, a medium-grained thermoplastic resin bonded diamond grinding head is used for grinding. Finally, it is finely ground and polished with the fine-grained Jiagang City grinding head of the same bonding type. In order to achieve a very flat degree of the overall marble floor, the surface layer is ground by about 1.5 mm, that is, 1 to 1.5 kg is worn out in 1 m2. It can be seen that there is a lot of debris that has been ground. In order to solve the problem that the cuttings and cooling water are not polluted, each grinding machine is equipped with a water circulation system, which uses a vacuum turbine to suck the waste liquid, and separates the cuttings into mud-like sediments and pumps them into the drying device. After being filtered, it is stored in a waste bag for centralized disposal. The purified water flows into the water storage tank for recycling by the grinder. Part of the water consumed is supplemented by an automatic replenishment system. Thanks to this water circulation system. Not only can it reduce labor, but it also increases the pure working time of the grinder. Therefore, the 5,000 m2 marble floor was refurbished and the task was completed in one month using only two artificial two grinders.
Generally, grinding and refurbishing marble floors require a combination of different diamond grinding heads from initial grinding to final polishing, which should be determined by experiment according to the specific conditions. The metal-bonded diamond grinding head is commonly used in the initial grinding stage. It has four particle size grades and uses SDA85+ synthetic diamond with a particle size ranging from 40/50 mesh to 50/70 mesh. After the initial grinding, a resin bonded diamond grinding head is used followed by fine grinding until polishing. The resin bonded diamond grinding head is divided into seven particle size grades, namely three coarse grain size grades, one medium grain size grade and three fine grain grade grades. The coarse-grained and medium-grained grades were nickel-plated synthetic diamonds of the PDA768 type and the PDA321N55 type, respectively. The fine-grained grade uses Micron MDA-type synthetic diamond micropowder. The coarse-grained diamond concentration was 21, the fine-grained diamond concentration was 11, and the diamond particle size was selected from the 80/100 mesh to 5 um range.
The use of diamond grinding and refurbishing marble flooring can significantly reduce grinding time and grinding and polishing costs, and improve the quality of grinding and polishing, especially the reduction of environmental pollution.