A sand-washing clarifier sees changing silt, clay and crusher fines while recycled water accumulates dissolved salts and residual chemistry. Polymer control must follow the solids load and the whole water-recovery circuit, not one clear grab sample.
Map the circuit
Record raw feed source, washing stages, screens or cyclones, clarifier feed, sludge withdrawal, filter equipment, clean-water storage and recycled-water fraction. Identify where fresh water, coagulant and polymer enter.
Note the residence between a polymer change and sampling point. Recirculation can delay or blur response if operators collect too early.
Track fines and recycle chemistry
Measure clarifier feed flow and solids or use a validated operating proxy. Record pH, conductivity and hardness. Watch for clay seams or crusher changes that increase ultrafines even when total tonnage is stable.
Compare product on actual recycle water. Increased salinity or hardness can alter polymer conformation and particle interaction, while accumulated dispersants or contaminants may reduce response.
Set a controlled dose range
Calculate active polymer against dry solids where possible. If the plant controls by water flow, record solids for every sample so the actual relationship is visible. Calibrate feeder, make-down water and solution pump.
Use small steps and wait for circuit residence. Define underdose signs—slow settling, cloudy overflow or fines escape—and overdose signs—light stringy floc, haze, sticky sludge or poorer filtration.
Balance water and sludge
Measure overflow turbidity or solids, water available to washing, blanket stability and sludge withdrawal. If sludge is pressed, add filtrate clarity, cake, cloth condition, cycle time and wash demand.
A higher polymer dose can improve overflow yet create a voluminous bed or slower filter. Select on total circuit performance and delivered treatment cost.
Use shift observations consistently
Create a short record for feed source, solids indicator, recycle conductivity, polymer stock condition, dose setting, overflow, blanket and filter. Use the same sampling locations and times. Photographs are useful only when lighting and stage are consistent.
Set warning limits that trigger checks of feed solids, preparation and equipment before product code is changed.
Review after process changes
Reconfirm the dose window after a major deposit change, new crusher, clarifier modification, filter cloth change or recycle-ratio shift. The former record is a baseline, not a permanent guarantee.
Send representative high-fines and normal samples when a new grade screen is required.
Build the supply request
Provide the circuit map, fines character, water chemistry, clarifier and filter data, current active dose, monthly demand, packaging and destination. Connect it to the sand-washing application page.
Diagnose a sudden overflow change
Check feed source and clay seam, clarifier feed solids, polymer feeder and water flow, stock tank age, injection blockage, sludge withdrawal and recycle conductivity before switching grades. A mechanical or delivery interruption can produce the same cloudy overflow as an unsuitable polymer.
Collect feed and overflow while the event is active and note the time relationship to crusher, cyclone, pump or wash changes. Samples taken after the circuit recovers may not contain the cause.
Coordinate clarifier and filter operation
Sludge withdrawal must keep pace with solids capture. If the blanket or hopper accumulates, fines can escape even when incoming floc is strong. Set withdrawal frequency or flow from measured solids behavior and inspect rake or cone condition where applicable.
For filter presses, track feed time, pressure rise, filtrate solids, cake release and cloth wash. Polymer selected only on clarifier overflow can create a bulky or sticky sludge that lowers the water-recovery benefit downstream.
Build a practical shift control sheet
Use one row for time, aggregate source, feed-flow or solids proxy, recycle conductivity, polymer product and lot, stock concentration and age, calibrated solution flow, overflow measurement, blanket or sludge condition and filter observation. Mark every setpoint change and the expected response time.
Define first checks for cloudy overflow, slow settling, rising blanket, sticky cake and low solution-tank residence. Consistent records let technical support distinguish feed, preparation and equipment causes from a true product shift.
Compare delivered treatment cost
Calculate polymer consumption with fresh-water replacement, recovered-water availability, sludge transport, filter cycle, cleaning and production interruption. A lower bag price can be outweighed by higher active dose or reduced water reuse.
Use measured normal and high-fines periods in the cost model so one easy operating day does not control the annual decision.