System and process for the continuous recovery of metals

Abstract

A system [100′] and process [100] for the continuous recovery of metals is disclosed. The system [100′] comprises a continuous acid wash system [10′], a holding tank [60], a continuous elution system [20′], a continuous electrowinning system [40′], a carbon regeneration system [30′], and a continuous carbon loading / adsorption system [70′]. The systems and methods disclosed overcome the disadvantages associated with current systems and processes which utilize batch process steps and equipment designed for batch processes. The systems [10′, 20′, 30′] are each configured to receive a continuous inflow of a solution or slurry and deliver a continuous outflow of a solution or slurry, without interruptions which are common with conventional metal recovery systems [9000′].

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to mining and metallurgical refining and more particularly to systems and processes for solvent extraction and electroextraction of metals.[0002]To this end, there are generally two main processes available for precious metal concentration and recovery: zinc precipitation, and electrowinning. Zinc precipitation involves crushing and grinding ore containing the precious metal (e.g., gold), and then combining the ground ore with a water and caustic cyanide solution. The resulting mud-like pulp is moved to a settling tank where the coarser gold-laden solids move to the bottom via gravity, and a lighter first pregnant solution of water, gold, and cyanide moves to the top and is removed for further processing. The gold-laden solids are agitated and aerated in a separate agitated leach process where oxygen reacts to leach the gold into the caustic water and cyanide forming a second pregnant solution. The second pregnant solution pass...

AI Technical Summary

Benefits of technology

This patent describes an improved metal recovery system that can recover metals from spent electrolytes. The system is designed to be continuous, meaning it can load and unload carbon, wash and strip it, form electrolyte, and win metal without stopping. This avoids the problems of traditional batch processes. The system also aims to improve efficiency by minimizing radiation losses, reducing power consumption, and preventing carbon breakdown and electrolyte loss. It also aims to maximize metal recovery and reduce the amount of unrecovered metal present in the spent electrolyte. The system includes various components such as acid wash, elution, and electrowinning, which can increase the temperature and pressure of solutions and include screen or filter elements.

Problems solved by technology

Some cathodes (e.g., wire cathodes, due to their small interstices) are not re-useable and must be recycled after processing, thereby increasing overhead / operational costs.

Moreover, such conventional batch acid wash processes 9100 typically discard expensive acid, caustic, and / or other reagents after each use.

This increases overhead (e.g., purchasing costs, disposal costs) and creates unnecessary harm to the environment.

Furthermore, every time a conventional acid wash vessel 9120 is drained and re-filled with a different rinsing solution, carbon (and precious minerals / metals attached thereto) may not be recovered due to system inefficiencies caused by heat, friction, increased pump residence time and exposure, an increased number of pipe elbows and valves, and the frequent discarding of spent rinsing solution which may still contain small amounts of loaded carbon and precious metal.

This increases both initial plant overhead costs and overall plant footprint.

This increases overhead costs (e.g., labor, maintenance), complicates production scheduling, and may cause harm to the environment.

Moreover, conventional elution systems have limited operating flow rates, temperatures, and pressures which drive up radiation losses and power consumption.

Additionally, the electroextraction of metals using the conventional “batch” electrowinning processes 9400 described above requires intervals of non-production downtime of the electrowinning cell 9420 and significant physical labor, which may contribute to premature cathode wear and wasted electrolyte solution 9530.

The process of using zinc to precipitate precious metals out of pregnant solutions is also costly, may be less efficient for large-scale operations, works for only certain metals, and may result in less precious metal recovery.

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