Process for Metal Seperation Using Resin-in-Pulp or Resin-in-Solution Processes

Abstract

A process for the treatment of solutions or slurries containing dissolved metals comprises the steps of (a) contacting the solution or slurry with an ion exchange resin that selectively removes one or more dissolved metals from the solution or slurry wherein the solution or slurry and the resin are introduced into a vessel or column via sub-surface means, (b) separating loaded resin from the solution or slurry, (c) eluting the one or more metals from the loaded resin with an eluting agent, (d) separating the eluting solution containing eluted metal ions from the resin; and (e) transferring regenerated resin from step (d) back to step (a).

1 . A process for the treatment of solutions or slurries containing dissolved metals comprising the steps of:
 a) contacting the solution or slurry with an ion exchange resin that selectively removes one or more dissolved metals from the solution or slurry, said contacting comprising introducing the solution or slurry and the resin into a vessel or column, wherein the resin is introduced into the vessel or column via sub-surface means,   b) separating loaded resin from the solution or slurry;   c) eluting the one or more metals from the loaded resin with an eluting agent;   d) separating the eluting solution containing eluted metal ions from the resin; and   e) transferring regenerated resin from step (d) back to step (a).   
     
     
         2 . A process as claimed in  claim 1  further comprising washing the loaded resin to remove entrained solids, solution or slurry prior to step (c); 
     
     
         3 . A process as claimed in  claim 1  wherein the slurry or solution is subjected to a pre-treatment that removes oversize particles and other contaminants therefrom prior to contacting or mixing the slurry or solution with the resin. 
     
     
         4 . A process as claimed in  claim 3  wherein the pre-treatment step comprises screening, settling, sedimentation, clarification, separation using hydrocyclones, or centrifuging. 
     
     
         5 . A process as claimed in  claim 1  wherein a low speed or a low shear mechanical mixer is used to mix the resin with the solution or slurry. 
     
     
         6 . A process as claimed in  claim 5  wherein the low speed mechanical mixer has an agitator operated such that a tip speed of the agitator is less than 4.0 m/sec. 
     
     
         7 . A process as claimed in  claim 6  wherein the tip speed of the agitator is less than 3.8 m/sec. 
     
     
         8 . A process as claimed in  claim 1  wherein the solutions or slurries are treated by addition of one or more reagents to adjust pH of the solutions or slurries to ensure that the target metal(s) remain in solution while at the same time ensuring that the ion exchange resin is operating within its optimal pH range for metal uptake and to remove potentially interfering non-target soluble metal ions by in-situ precipitation, wherein precipitation of the non-target soluble metal ions occurs in a vessel in which step (a) takes place. 
     
     
         9 . A process as claimed in  claim 8  wherein the non-target soluble metal comprises ferric ions and the process comprises adjusting the pH in step (a) to a value in the range of about 2.8 to 3.8. 
     
     
         10 . A process as claimed in  claim 8  wherein pH adjustment is achieved by adding a solid neutralising agent to the solution or slurry and the solid neutralising agent is screened to remove oversize particles having a particle size greater than a predetermined size prior to mixing with the ion exchange resin. 
     
     
         11 . A process as claimed in  claim 8  wherein pH adjustment is achieved by adding a solid neutralising agent to the solution or slurry and the solid neutralising agent is treated to remove oversize particles having a particle size greater than a predetermined size prior to mixing with the solution or slurry. 
     
     
         12 . A process as claimed in  claim 1  wherein the particle size of the resin has a narrow size range. 
     
     
         13 . A process as claimed in  claim 1  wherein soluble iron removal from the solution or slurry is required and is achieved by pH adjustment and ferrous iron is oxidised to the ferric state in order to induce precipitation of the soluble iron, wherein an air/slurry contactor system is provided to facilitate oxidation of ferrous iron to the ferric state. 
     
     
         14 . A process as claimed in  claim 1  wherein subsequent to resin contact with the solution and/or slurry, the loaded resin is separated from the treated solution and/or pulp in step (b) by use of one or more screens. 
     
     
         15 . A process as claimed in  claim 1  wherein transfer of the resin is achieved using dense phase hydraulic conveying. 
     
     
         16 . A process as claimed in  claim 1  wherein transfer of the resin is achieved using water eduction, low shear recessed impellers, or peristaltic pumps. 
     
     
         17 . A process as claimed in  claim 1  wherein the percentage of resin solids in the solution or slurry is below 50%. 
     
     
         18 . A process as claimed in  claim 17  wherein the percentage of resin solids in the solution or slurry is below 40%. 
     
     
         19 . A process as claimed in  claim 1  wherein the resin is transferred in water and the process further comprises recovering or recycling the water in a closed or partially closed loop. 
     
     
         20 . A process as claimed in  claim 1  wherein washing and/or elution is conducted such that there is an upflow of water or solution which causes fluidisation or entrainment of the resin in the upflowing liquid. 
     
     
         21 . A process as claimed in  claim 20  wherein the resin overflows from a process vessel over a screen to effect separation of the resin from the liquid. 
     
     
         22 . A process as claimed in  claim 20  wherein transfer of the resin to a next stage in the process occurs without passing the resin through a pump or pumps.