Is the re-pulping for Concentrate stored in dams, or in some other way? If its stored in dams, then hydraulic washing into a sump works, but usually that means very low percent solids. You will need to thicken if you want higher solids for say grinding. But if storage is in dumps then trommel screens can work well, again it depends of the percent solids(density) you need for whatever the next stage of the process is.

Hi Tony, Stockpiles. Concur regarding trommels. Slurry SG 1.62

Just mainly interested in other process options that I may not know of and haven't already listed in my post.

Stockpiles can be easier to obtain the percent solids you need, but they inherently have lumps that have been cause by "baking" or by partial oxidation, so trommel is best and the over sized lumps will have to be treated separately. Whats the next stage in the process? Grinding to expose fresh surfaces for the possibly upgrading the concentrate? As mentioned send me some info and I can help you with some more thoughts.

There were lots of ideas as above and it would be worth checking the thread.
It was called "Re-pulping filter cakes from a plate and frame filter press". We are going with the repulping tank idea as I will have a fresh concentrate, no head height, limited budget and no surge thickener.

I would like to have more detail of requirement at your end. I had seen operation and involved in re pulping circuit for iron ore tailing benefaction on our HGMS. Depending upon the raw material and product requirement a slight grinding, attrition scrubber, de sliming screens with or without hydro cyclones of classifying spirals along with pumps can be used.

May be the above equipment will exceed requirement at your end need to address specific to your requirement.

It is not clear to me what is meant by "repulping of concentrate". Are we talking of rougher/scavenger concentrate? Please elaborate the purpose for which a concentrate has to be repulped in your operation.

Repulping of pyrite concentrate that has been stockpiled over a period of time to form slurry with a slurry density of 1.62-1.68tonne/m3

If it has been stockpiled for a long time, please check whether the mineralogy/size distribution have changed before you think of processing. What is that being attempted to recover?

Barrick, Porgera had a similar situation as you. They too had sulphide concentrate that was located in an overflow dam that had a hdpe lining.(i.e. similar to a tailings dam/pond) The concentrate had been deposited over a period of time and had settled out. Thus, they used high pressure monitor guns to wash the sulphide concentrate to a penstock that had a submersible pump and it was pumped to the current concentrate thickener and carbon in leach circuit to recover the gold.

KCGM Gidji roaster has such a repulping circuit. Gold bearing pyrites are floated at Fimiston plant. Float cons are dewatered using vacuum filters and stockpiled at the Fimiston plant site. The concentrates are then transported to the Gidji Roaster site, about 20 km away from Fimiston site, using dumper trucks. At the Gidji site the trucks dump the cons into hoppers. Concentrates are then flushed out of the hopper (bottom exit) using pressurized fresh water into a large mixing sump. Repulped concentrates are then pumped from the mixing sump to a repulp thickener where the pulp density is adjusted to a desired level before storing in storage tanks. These tanks are used as feed tanks to the roasters. But after a recently commissioned IsaMill M10000 UFG circuit these roasters will be shut down. Therefore these storage tanks are now feeding the UFG circuit. This is a brief description of the repulping circuit at Gidji. I was the Principal Process Engineer in the design of this new IsaMill M10000 UFG circuit. Hence i have detailed knowledge of this repulsing circuit. Hope this helps.

I have worked with three different repulping set ups, two of them originally had a small bucket loader or manual feeding a hopper which was covered by a sloped fixed grizzly into what looked like cheese mixers - like opposed mixing screws.

In one case, this fed onto a conveyor belt, into a tank with water level and addition and an offset agitation Level needed to be maintained in the tank and you could see that originally the conveyor had a weight-o-meter to allow proportional water addition. This was a pig to run to be honest, More screening would have helped a lot and we ended up putting a sieve bend downstream of this part of the process. Chunks of con would get stuck in the screws, in the tank and in the pump suction. If there had been the physical foot print to screen it while adding water it would have helped. Either a scrubber/modified trommel or a screen would have meant less downtime. We were constrained by footprint and capital.

In the other case were used to batch re-pulp prior to feeding onto a filter belt for drying to a different depth and consistency. This material wasn't as hard - hadn't been sitting around for months. Still got chunks caught in the mixer blades occasionally.

Another place we ended up driving D10 over the con stock piled to break it up (very hard crust forms on some concentrates depending on how susceptible they are to oxidation). We put the con through a static grizzly with a loader prior to trucking down to a sump to re-pulp by hosing into sump pumps into a thickener. If you can't afford a thickener (or don't have a spare sitting around) you can make a quasi-thickener with a sloped bottom tank or conical bottomed tank where you also design in an overflow - it’s the poor man’sthickener, but it can get the job done if your capital won't stretch that far. I know of other places that have needed to use mobile crushers to break up their con if it has oxidised into a crust or simply dried out too much. 

Thanks for taking the time to write your comments here. Much appreciated. I can sympathize with "running the pig". Have had to put lipstick on many "pig" unit operations as an operator and then Met over many years to try and make them operate in a sort of decent manner!