Smopex
Member
- Joined
- Jan 18, 2013
- Messages
- 18
nickvc said:The ST team.
Thank you for further clarification on your products.
You're welcome
A stockpot is what most members use to store waste solutions containing values which are been cemented to recover the values.
Using your calculation of 20 grams per 10 litres of solution with 0.5 grams per litre or less it makes some sense but what if the solution is only very low PM bearing say under 0.1 grams per litre do we still need to use 20 grams per litre and how many times can the Smopex be used, is it a one off use or will it continue to function until saturated with values, also how can we tell when the Smopex has ceased working, is there any visible way to tell.
If the solution was less than 0.1g/L (100ppm) then yes less Smopex would be required.
When we are assessing our customers solution, we run a number of experiments that are designed to calculate which of our scavengers are best at recovering the metal in question, how much is needed, how long is needed and the optimum temperature. We also calculate the loading of pgm onto the fibre to ensure the economics stack up. Of course we understand that this process is not always possible, but without the key data generated from these tests it is difficult to be too specific about the conditions required for successful recovery. However, we can of course make recommendations on what we do know!
Our scavengers work by chemically bonding to the pgms in solution. As this is a chemical process, we can calculate how much Smopex is needed to recover a certain amount of metal, providing we know the concentration of the pgms in question. Each fibre has a scavenging ‘capacity’ (imagine a sponge that can absorb liquid, once the sponge is saturated, it cannot soak up any more liquid). For anyone who’s interested the capacity of Smopex is measured in millimoles per gram or mmol/g, so by knowing we have say x amount of gold, we can calculate the mmol equivalent in gold and then equate that to the mmol of smopex required and convert back to g (or kg). It’s easier than it sounds.
So, to generalise on this without the chemistry bit, we recommend the following calculation:
Quantity of Smopex (g)=Volume of solution (L)×Metal in solution (g/L) ×40
Or if you work in ppm or mg/L then:
Quantity of Smopex (g)=Volume of solution (L)×Metal in solution (ppm) ×0.04
This is a rough guide and without analysis will give you a good idea of how much Smopex to use.
Knowing when to stop treatment is either based on:
-the Smopex has become fully loaded
Or
-the metal has been fully recovered.
Generally we use an excess of fibre so the first instance does not become a limiting factor. The second is usually measured by analysis. However, depending on the metal compound to be recovered, a visual change in either the solution or the Smopex can be observed.
Here's a lab image of filtered Smopex 105 loaded with platinum which causes a colour change from beige to bright yellow (chloroplatinic acid from hydrochloric acid, pH<1)
Smopex can be used multiple times until fully loaded. However sometimes this isn’t advised as metal could potentially exchange back off the fibre into solution under the right conditions, but this is not normally observed.
As an example I have a solution that has Pt and Pd around 80 litres and it's contents are around 25 grams in total of those two metals, would I need 1600 grams of Smopex to recover these metals and after the solution has been treated can the Smopex be used to recover values from further solutions or is it now useless?
So 80L at 25g metal is 0.312g/L or 312 ppm. This would require apx 1000g Smopex (using the above calculation, this maybe an excess). For this amount of metal I wouldn’t suggest re-using the fibre. For lower concentrations of pgm you could as they’d be less risk of leaching metal.[color]
The idea percolating through my non chemists head is that if Smopex will work until saturated that the solutions from our stockpots after cementation could be either filtered through Smopex, have a bed of it to pour our waste into or a simple bucket with holes in into which waste solutions could be poured to collect any values still present but allow the solution to be drained away for waste treatment but all these ideas are based on whether Smopex works constantly or just once, also bear in mind assays for many members are expensive so a visual method to tell if it is loaded or not would really help the costs.
A column or filter bag would work ideally here where you’d have a fixed bed of Smopex and the solution is pumped through the Smopex. The Smopex is then changed once it’s fully loaded (or no longer recovers any values). Here's an example of this setup we currently have in operation:
No problem at all we’re always happy to discuss any questions you and the other members of the forum have.I'm sorry if it seems I'm constantly pushing you but the members here by and large are hobbyist or small time refiners and every cent counts and while your products seem to be what we all could profit by I just want clarification so everybody can see the benefits and usability against costs and time spent using it.
Yes there is a limit as stated above; it’s based on the chemical capacity of the fibre which we measure in mmol/g. Another factor is the metal species present, not all species have the same reactivity or affinity for Smopex. We can advise on this if you’d like more information.Another point I wished to raise is, is there a limit percentage wise that Smopex can scavenge values from solutions or is it down to the time in contact and the actual make up of the solutions, such as the acids and base metals in it.
Edited for a first her query.