HIGH PROFILE
Fines from waste
AKW Equipment + Process Design outlines how its technologies can help mining operators recover fines and conserve water in the form of its innovative AKA-SILT system
Mining operations require large amounts of water and generate tailings that have an impact on the environment . The R & D department of AKW Equipment + Process Design has been engaged for many years in the development of technologies helping quarry and mine operators to optimise their water consumption , maximise the valorising of fines and extract value from tailings .
As not all companies face the same constraints , the customisation of treatment solutions is an element of differentiation between suppliers : key is not to over engineer a solution , but to find the right balance between the need to recycle water , the recovery of fines , the context in which the operator works and the level of investment available and required for the implementation of the different solutions .
Looking at industrial minerals , and taking the example of silica sand , it is a fact that most of the existing processing plants are not designed for ultra-fine sand recovery , and therefore a significant amount of product is lost in the 0-150 µ m range . This leads to higher solid loads of the wastewater circuit which becomes more challenging to manage and operate .
In order to maximise the recovery of fines , as well as contribute to a better water management system , the AKA-SILT System – a combination of ultrafine hydrocyclone classification with dewatering of critical fines – has been developed , tested and meanwhile realised in industrial scale at several places .
How does it work ? From an existing treatment plant , approximately 200 m ³/ h of solids-loaded
process water is fed to a pump sump via a pump . With an additional wear resistant slurry pump , the suspension is fed to a first AKA-SPIDER hydrocyclone classification distributor . An installed antiblocking filter , AKA- STRAINER , retains any larger particles that may be present and thus avoids blockages in the distributor , which could lead to variances in the classification . The material is classified at 10 µ m by using proprietary AKA-VORTEX high-performance polyurethane hydrocyclones .
The hydrocyclone overflow < 10 µ m is directed into the wastewater treatment line , whereas the hydrocyclone underflow fraction > 10 µ m is directed to a second AKA-SPIDER hydrocyclone stage that will thicken the suspension prior to its dewatering into a marketable ultra-fine sand ( 10-150 µ m ). In parallel , the solid content being significantly reduced in the wastewater treatment line , the handling of this circuit is significantly eased and can run with a higher efficiency and ecological footprint , especially as result of a lower usage of flocculant .
The AKA-SILT system can be installed as an additional unit in existing plants . By maximising the total material utilisation yield of a quarry and optimising the overall wastewater treatment flow , it allows the customer to reach a high environmental standard without compromising on its products quality and overall profitability . IM
OCTOBER 2021 | International Mining 35