Silica Sand Washing plant installed by CDE Asia
The successful commissioning of a Silica Sand Washing plant, in India, has added a new feather in CDE Asia’s cap. Having pioneered the concept of washing construction sand & aggregates in India and its neighboring countries, CDE Asia is now poised to demonstrate the value-addition of production and quality improvements of washing silica sand through its system.
Silica sand is used in the foundry industry and in the manufacture of glass. The naturally available Silica sand contains lots of clay and particles, both above and below the desired sizes of specified grains of sand. Proper washing and sizing is important to make the product saleable.
The Silica Sand Washing plant has been installed for Atharv Mines Pvt. Ltd. and the plant is located in the Sindhudurg district of Maharashtra. Atharv Mines did not have a mechanized operation prior to installing the CDE system and manual operations did not result in quality improvement of the silica sand, thereby making the sand not saleable to glass and the foundry industry. The manual process was also inefficient.
The CDE Process
Stage 1 - Feeding Circuit: The feed sand is received in a 20 ton capacity Hopper which is fitted with a belt feeder for effectively feeding 80tph of sand to the circuit. These are provided with a VSD and belt-weigh system and thus feed to the system can be controlled and monitored continuously. The feeder then feeds sand to the AtroFeed at a rate of 80tph. High pressure water is added to the AtroFeed to break down lumps of sand and dislodge the clay from sand particles. The slurry formed due to addition of water is delivered to the sizing screen. Primary attrition is provided to the sand by the AtroFeed to dislodge lumps of sand and to clean the surface.
Stage 2 - Fines washing: The Slurry will be fed to single-deck Rinsing Screen. The unit works to remove the liberated fines from 600 micron efficiently. This stage gives us our first product of coarse sand onto the stockpiler. Undersize material of 600 micron will be fed to an EvoWash which is an integrated and compact washing unit including the required sump, heavy duty pump, and hydrocyclones. Secondary clay attrition is offered to the minus 600 micron material by the heavy duty slurry pump while feeding to the Hydrocyclone at high velocity.
Here material will be separated at 106 µm size in a flat bottom type cyclone. The cyclone underflow of size (+)106 µm will be dewatered in the Dewatering screen and integrated with the EvoWash. Dewatered products will be stockpiled separately.
An additional hydrocyclone is provided for separation of 70 micron or below, when flat bottom cyclones are not required in the system. The additional cyclone is isolated with a knife gate valve for on/off operation.
Stage 3 – Water Management System: The combined slurry from the cyclones will pass to the AquaCycle High-Rate Thickener to rapidly settle and control the tailings. Dense sludge of ultra-fines (approx. 300g/litre) will be discharged. Clean recycled water is immediately released from the Thickener and is recycled to the washing system through the Water tank.
Atharv is expected to produce 50 tph Silica Sand for use in Foundry and Glass making (as per feed sand quality) to supply to local foundry and to glass manufacturing units. The Sand produced through the CDE washing plant will meet customer specifications and shall be acceptable to the specific industries that Atharv wishes to cater to. Nittin Jaju, Director Atharv Mines, after commissioning of the plant has remarked “I am highly impressed with the detailed planning of the plant and the cooperative staff of CDE.”