Solvent Extraction

Challenges

Today, many operations are finding their capital budgets declining. Companies are trying to squeeze everything they can from their plants to achieve higher throughputs with minimal spending.

Ore grades are declining, pulling product liquor solution (PLS) grades lower, too. Higher flows must be pushed through solvent extraction to maintain production levels at the plant. This can increase entrainment problems. And, extraction loading limitations being what they are, it still may not be possible to reach the throughput you’re after.

Ore grades are also becoming more complex. More and different impurities mean additional solvent extraction scrubbing or purification steps are required to maintain strip-liquor purity. Crud management systems are labor-intensive, and if they’re done poorly or improperly, they can reduce plant availability and performance.

Fire is an inherent risk that must be managed at every solvent extraction circuit, and destructive fires have occurred at several plants. Best practices and insurance requirements continually rise. For new plants, fire prevention and protection design can be expensive. Old plants may require retrofits in order to be code compliant.

Organic extractants may degrade over time, and must be continually monitored. Sub-optimal extractants can lead to poor plant performance, and require organic treatment stages to improve their function.

Capabilities

Solvent extraction plant assessment and improvement

Assessments and resulting modifications to processes and equipment can increase flow throughput by as much as 40%. We troubleshoot and offer solutions. A review may include physical and chemical performance, hydraulic behavior, process control improvements, and fire system assessments.

Test work

We perform test work using our own equipment and personnel, determining the sizing of mixers and settlers for each step of a circuit. Test work determines the settler sizes and number of stages for extract, scrub, strip, wash (as needed), the sizes and agitation requirement for mixers, and the chemical performance. We guarantee the outcomes.

Custom design approach

At a new plant, test work allows custom sizing for every settler. This minimizes plant capital cost, organic volume, and footprint without affecting performance. For an existing plant, the approach identifies major opportunities to improve performance and increase throughput. Hydraulic modeling helps minimize power input to the organic/aqueous mixture, avoiding the formation of emulsions and reducing organic degradation.

Solvent extraction technologies

Our proprietary technologies improve the operability and efficiencies of solvent extraction circuits. These include the smooth-flow, settler-feed launder to eliminate turbulent flow; distribution array to improve phase separation times; re-entrainment prevention devices; drop bottom and phase splitter for entrainment; and settler size minimization. All can be retrofitted to existing plants or designed into new ones.

Specification and integration of other required equipment

Our experts thoroughly understand different vendors' equipment. We're experienced with tools in solvent extraction circuits, like pumps, multimedia filters, carbon columns, filters, centrifuges, and instrumentation, including hazardous area definitions that can affect selection or specification.

Fire prevention and protection

Fire and explosion modeling is required for a safe plant layout. Fire design scope depends on your risk objectives, insurance and code requirements, and a thorough understanding of the process and hazardous area basis. Early fire system definition is critical, because it's integrated into the overall emergency services system for your operation as well as design aspects: bund design, equipment selection, materials selection, static elimination, and isolation.

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