Abstract: The rotating shaft is sealingly mounted in a wall of the vessel by a liquid-tight lip seal. In order to avoid undesired depositions on the seal the latter is made of electroconductive material and connected to the anode of a source of electricity the cathode of which is connected to a counter-electrode within the vessel.

Abstract: There is described a pressurized filtration system for removing suspended solids from a liquid which comprises two enclosed filter vessels each containing either a removable filter bag or cartridge. The vessels are located in parallel in the circulation line of a pump which pumps the liquid from a bulk storage vessel through only one filter vessel at a time, this being controlled by a valve system in the circulation line to the filter vessels. Liquid forced through the filter vessel in use is pumped to a liquid storage vessel via a non-return valve located in the outlet line from each vessel, the outlet from each vessel having a branch connection to a shuttle valve, the outlet from which is connected via a non-return valve to the suction side of the pump, whereby when liquid is being pumped through one vessel the shuttle valve is shut against the flow of liquid therethrough but is open on the other side so that the liquid can be sucked out of the other vessel.

Abstract: An electrolytic metal recovery cell is described in which a cylindrical cathode is mounted for rotation in a housing having an inlet and outlet for solution from which metal is to be recovered. The housing contains an anode and a cutter blade is mounted so as to be capable of removing metal deposited over the whole face of the cathode when the cell is in use. In order to control the operation of the cell, electrical means are provided for operating the cutter blade at predetermined intervals of time irrespective of the electrolysis conditions and for operating the cutter blade when a monitored cathode potential deviates a predetermined amount from a desired value.By this means the use of previously proposed scrapers and their attendant disadvantages are avoided and the cell can be easily controlled either under steady state electrolytic conditions or even when there are large variations in the concentration of the metal ions in solution.

Abstract: This invention relates to the recovering of metallic silver from photographical bleach-fix baths. An electric current is passed through a bleach-fix solution containing silver ions and ferric ions, which solution has been brought to a predetermined redox potential by the addition of a reducing agent. The cathode is of the type wherein reduced silver ions can deposit thereon as metallic silver. The redox potential of the electrolyte solution is continuously monitored and a reducing agent is added automatically when the redox potential rises above a predetermined level. When the redox potential drops below a predetermined level the addition of the reducing agent is automatically stopped.

Abstract: This invention relates to the recovering of metallic silver from photographical bleach-fix baths. An electric current is passed through a bleach-fix solution containing silver ions and ferric ions, which solution has been brought to a predetermined redox potential by the addition of a reducing agent. The cathode is of the type wherein reduced silver ions can deposit thereon as metallic silver. The redox potential of the electrolyte solution is continuously monitored and a reducing agent is added automatically when the redox potential rises above a predetermined level. When the redox potential drops below a predetermined level the addition of the reducing agent is automatically stopped.