The fine sand recycling machine is the "resource guardian" of the quartz sand
washing production line, responsible for recycling 0.1-0.3mm fine sand from
wastewater. If the recovery rate is low (below 85%) and the sand content in the
wastewater is high (over 0.5%), it will cause waste of raw materials,
sedimentation in the sedimentation tank, and increase the cost of dredging.
Based on practical experience, summarize the three-step troubleshooting method
to quickly improve the recycling efficiency.
Step 1: Check the cyclone and dewatering screen - the core components
determine the recovery efficiency
The separation effect of the cyclone and the filtration capacity of the
dewatering screen are the main reasons for the low recovery rate.
Improper or worn parameters of the cyclone: feed inlet diameter is too large
(exceeding the design value by 20%), flow rate slows down, and fine sand
separation is not thorough; If the height of the overflow pipe is too low, it
will bring fine sand into the wastewater; The inner wall wear exceeds 3mm, the
flow field is disordered, and the separation accuracy decreases. Parameters need
to be adjusted according to the particle size of fine sand: recover 0.1-0.2mm
fine sand, select a Φ 150mm cyclone with a feed inlet diameter of 25mm and an
overflow pipe height of 180mm; replace the high wear-resistant polyurethane
cyclone (with a lifespan three times longer than cast iron) to ensure smooth and
wear-resistant inner walls.
Blockage or incorrect inclination angle of the dewatering screen: If the mesh
size of the screen is too small (such as 40 mesh), fine sand is prone to
leakage; Excessive mesh size (such as 100 mesh) makes it difficult to discharge
wastewater with high moisture content; Screen clogging (adhesion of mud powder)
will reduce filtration efficiency. It is recommended to use a 60-80 mesh
stainless steel sieve and rinse it daily with a high-pressure water gun
(0.5MPa); Adjust the inclination angle of the screen surface to 12 ° -15 °,
taking into account both fine sand recovery and wastewater discharge, to avoid
the loss of fine sand with water.
Step 2: Calibrate operating parameters - parameter imbalance reduces the
recovery effect
Improper settings of pump pressure, feed rate, and overflow rate directly
affect the separation efficiency.
Pump pressure too low or too high: pressure below 0.2MPa, insufficient flow
velocity in the cyclone, and ineffective separation of fine sand; Exceeding
0.4MPa, the flow rate is too fast, and fine sand is easily washed away to the
overflow outlet. Monitor with a pressure gauge, adjust to 0.25-0.35MPa, and use
a variable frequency pump for precise control to ensure stable flow field inside
the cyclone.
Overloading or uneven feed rate: exceeding the rated processing capacity
(such as 20m ³/h, actual 25m ³/h), overloading of the cyclone, incomplete
separation; The feed fluctuates frequently, the pump pressure fluctuates
greatly, and the recovery rate is unstable. Use a flow meter to control the
quantity and maintain it at 80% -90% of the rated value. Install a stabilizing
tank to allow the wastewater to enter the cyclone evenly and avoid flow
fluctuations.
Improper control of overflow volume: overflow volume accounts for more than
30%, and the wastewater contains a lot of sand; Below 20%, fine sand is prone to
accumulate and block in the cyclone. By adjusting the valve of the overflow
pipe, the proportion of overflow flow is controlled at 22% -28%, and the
turbidity of the wastewater is observed. Gradually fine tune it until the
wastewater is clear and the fine sand recovery rate meets the standard.
Step 3: Adaptation of materials and daily maintenance - raw material
issues+maintenance deficiencies exacerbate malfunctions
The sludge content in wastewater and equipment maintenance can affect the
stability of recycling.
High mud content or fine sand particle size in wastewater: if the mud content
exceeds 5%, the mud powder will clog the cyclone and sieve, reducing the
separation efficiency; Fine sand particle size<0.1mm, easily lost with
wastewater. Before recycling, a sedimentation tank should be added to remove
some of the mud powder; When recycling ultrafine sand (<0.1mm), replace the
high gradient cyclone with a 100 mesh screen to improve the fine sand retention
capacity.
Maintenance deficiency: impeller wear of slurry pump (diameter reduced by
5%), pump pressure drop; The dehydration screen bearing is short of oil and the
operation is stuck. Check the pump impeller weekly and replace it when the wear
exceeds the limit; Check the bearing temperature daily (≤ 65 ℃) and add lithium
based grease every week; Clean the residual mud powder in the cyclone and sieve
every month to ensure smooth operation of the equipment.
By following the above three steps, the recovery rate of fine sand can be
increased to over 95%, and the sand content in wastewater can be reduced to
below 0.2%. If there are still problems, it is recommended to contact the
manufacturer to test the compatibility of the equipment and ensure that it
matches the demand for quartz sand fine sand recovery.