The Problem
A company that deals with Victorian landfill waste specializes in converting it into valuable-sized aggregates. Their washing plant can process approximately 100TPH of various feed types. To recycle the process water, they treat the fine tailings through a thickener and a solid bowl centrifuge. The thickener requires combined treatment with a coagulant and a flocculant, followed by a secondary flocculant to process the thickener underflow through the solid bowl centrifuge. SciDev was engaged to address the challenging thickener processing conditions they were experiencing. These conditions resulted in:
- Poor overflow quality, resulting in solids being recycled back into the washing plant and contaminating the sand products
- High dosages of coagulant and flocculant were required
The Solution
Treatment with ClariVie44®, a water conditioning agent, eliminated the need for a conventional polymeric coagulant
Use of ClariVie44® provided net savings of over $5,000 per week by eliminating the use of coagulant resulting in a significant improvement in thickener overflow.
Overflow solids reduced and fine solids accretions on thickener overflow launder eroded and disappeared.
Coagulant dosage at the thickener was reduced to zero.
Reduction in flocculant consumption across thickening and centrifugation and reduced make-up water demand.
Results
Initial laboratory tests showed ClariVie44® exhibited significantly better performance than conventional coagulant (used with the same flocculant):
- ClariVie44®: 15 m/h settling rate, <40 NTU turbidity at 80g/t d.s. floc, 1 g/L ClariVie44®
- Coagulant: ~20 m/h settling rate, >450 NTU turbidity at 100g/t d.s. floc, 600 g/L coagulant
