Sorption process has great importance during the recovery of gold, silver, uranium and others from ores in hydrometallurgy. There are several ways to arrange this process in practice. One of the most common ways but currently considered as outdated is to use devise of Pachuca type.
Pachuca tanks (Pachuca) – are vertical continuous devices where mixing and pumping of the pulp is done due to the energy of compressed air by means of built-in air lifts. Pachuca devices are mounted in series and the pulp coming in the first tank is transported by gravity flow in one after another till the last tank.
PACHUCA TANKS HAVE TWO BASIC KINDS
- Carbonitriding Pachuca
- Sorption Pachuca
Sorption Pachuca tanks have drainage facility to separate the sorbent (cationite active carbon etc.) from the pulp, allow also to carry out the carbonitriding of pulp and the concentration of extractive component on the sorbent surface simultaneously.
APPLICATION OF PACHUCA DEVICES HAS SEVERAL DISADVANTAGES FOR SORPTION
- High single load of sorbent;
- Large number of sorption degrees and large area occupied by the equipment;
- High air consumption for mixing and transporting of sorbent and pulp;
- Active mechanical exposure on sorbent which results in the quick destruction of grains;
- Increased consumption of sorbent during its multiple passes on the drainage surfaces and return back to the device;
- Possible slip of sorbent and pulp through Pachuca is quicker than required contact time.
In spite of these disadvantages and trend to replace Pachuca with more modern devices this technology is still widely used at the enterprises.
More modern way of hardware solutions which is more widely used recently is sorption column of different types. Sorption columns are also vertical continuously operating mass-transfer devices which are remarkable for methods to mix and separate the sorbent and the pulp.