Wet grinding vs Dry grinding

The scheme of wet grinding of phosphate rock to superphosphate production is an alternative to dry grinding circuit, currently used by the company Rotem Amfert Negev.


For its techno-economic evaluation is proposed the circuit apparatus, comprising: a ball mill operating in a closed circuit with a multifrequency screener; stage of dewatering of crushed product comprising a hydrocyclone and multifrequency screener, stage of the thickening of hydrocyclone overflow and dewatering screeners undersize product in the sump with the return sludge for dewatering and roar and clarified water - in the grinding circuit.

The initial size of phosphate rock fed to the cycle of wet milling is about 10-0 mm or an average of 3% larger than the class of 4 mm (range size can be + / - 20%).

Required end fineness of grinding: no more than 5% passing 150 microns or 100 #.

To achieve the required size grinding is proposed to use a ball mill operating in closed circuit with multifrequency modular crash, equipped with spray systems oversize product water.
Dewatering crushed rock is also recommended to use multi-frequency rumble.


As the solids content in the final screen undersize product that works in a cycle of crushing, will be approximately equal (30-35)%, then, prior to thickening undersize product before dehydrating crash, it is recommended to install a hydrocyclone, concentrated product which is delivered to a roar.


Predicted final moisture oversize product dewatering screen will be about (15-20)%. Draining the cyclone and dewatering screen Undersize be sent to the sump. To obtain the clarified water back advisable to file a settler flocculant and sludge dewatering to return to power noise.
Reverse water can be used to dilute products, directed to the closed-loop grinding.


Dr. Grigory Kosoy, Kroosh Technologies ltd