|Rotex Standard Ultra Series Silver Recovery Systems.|
| Low Cost|
The Rotex Ultra series silver recovery units are available in 3 sizes or models, as well as being available in an automatic version. All three are intended for use either batch or continuous-flow operation. They are designed to electrolytically remove dissolved silver from thiosulfate solutions - both sodium thiosulfate as well as ammonia thiosulfate - common to photographic fixer baths such as:
Rotex Ultra units are not intended to remove silver from solutions containing developers or bleaches such as found in E-6 color slide fix, dichromate found in full reversal microfilm or EP-2 color print.
ADJUSTABLE PLATING CURRENT
Rotex Ultra series silver recovery units have power selection switches to adjust the plating current. This allows the plating current to be set for the optimized silver recovery over a broad range of conditions. In practice the current
|is set as high as possible without causing the deposited silver to become to dark.|
Rotex Ultra silver recovery units feature a motor-driven cathode to continuously renew the silver ion in the liquid contacting the cathode, also called the cathode "junction". Without agitation of the solution the junction would be quickly depleted of its silver ions and undesirable chemical reactions would occur. The rotating cathode allows for a compact machine and was pioneered, patented and became the basis of the name "Rotex".
Rotex Ultra silver recovery units are direct-drive gear motors without belts, gears, drivers, bushings or other components which require service or replacement. The gear motor shaft is sealed so that the fumes from the fixer will not enter the electrical enclosure.
The power supply features a center-tapped transformer that is wound for low impedance and cool, efficient operation. The plating current is rectified from AC (alternating current) to DC (direct current) by a full way center tap bridge rectifier that operates more efficiently (makes less heat) than other types of rectifiers. The full-wave center tap bridge rectifier is cooled by a fan that also draws fresh air into the power supply enclosure, thus ensuring long life. An ammeter is featured to indicate the plating current in "Amperes" and a circuit breaker is provided for convenient protection - no fuses to replace ever!
Plating current is applied to the cathode shaft by a unique contact arrangement using high silver contents contacts for exceptionally long life... no brushes to replace or slip rings to oxidize! The Rotex exclusive contact system was pioneered over 25 years ago and continues in its improved form to be the most effective method yet designed. This superior contact arrangement allows Rotex Silver Recovery machines to operate at higher cathode speeds for superior silver plating performance.
Silver plated onto the Rotex Ultra cathode may be easily dried and "cracked" and removed from the cathode as "photographic chip" or "flake". It may be easily smelted into pure silver as its purity is usually 95% or better. ("Coin" silver, by contrast, is 90% silver and 10% copper). It is not unusual for clean, dry chip and flake to be sold for 85 to 87% of its commodity value. Larger amounts may be valued as high as 92%. The commodity value of silver is listed in nearly all daily newspapers.
Silver trapped in steel wool canisters, on the other hand, is in a "sludge" of unknown concentration. The sludge requires special fluxes to smelt and thus has far less value than clean, dry chip and flake. Also, a sample must be assayed to determine the silver concentration. Because of the assay charge and higher smelting cost the value of the trapped silver in the sludge may or may not offset the cost of the canister and the freight. Nonetheless, use of the steel wool canister is recommended to satisfy codes. Violators may be penalized on a "per day" basis.
CONTINUOUS FLOW-THROUGH OPERATION
The Rotex Ultra series may be used to continuously desilver fixer overflow from a processor by connecting its inlet fitting directly to the processor fixer overflow. The Ultra is wired to operate anytime the processor is operated. A timer can be connected between the Ultra and its power source if the user intends for it to operate during selected hours. The outlet or "overflow" fitting on the Rotex Ultra is connected to a steel wool cartridge to trap residual silver as required b most state and local codes. On occasion, a processor may see varying usage rates with peak periods of use followed by idle periods. The peak period may overflow more silver than the Ultra can recover because of the high flow rate. In such an installation, a Rotex Autometer may be added between the processor and the Ultra inlet. The Autometer will precisely meter a continuous flow rate into the Ultra, and, during an idle period when no flow is available from the processor, the Autometer simply switches the Ultra off and waits until more fixer leaves the processor.
The Rotex Autometer may also be used to collect fixer from more than one processor overflow from metering through a single Ultra, thereby eliminating the need for an additional Ultra and it's "tailing" steel wool canister.
The Rotex Ultra series may be used to desilver a batch at a time if desired. The fixer is usually collected in plastic bottles at the film or paper processor(s) and poured into the plating tank. At the end of the time another estimate is made and an additional period of desilvering is accomplished at a lower current setting to remove the reduced concentration. A concentration of less than 50 PPM is likely to be achieved, although, some users report final concentrations below 10 PPM. The spent fixer is then trickled through a steel wool cartridge or canister to remove the residual silver as required by most state and local codes. A simple globe valve may be added to the Rotex Ultra at a slight additional price to limit the flow rate to the canister. Instructions are included in the Operators Manual. Due to the very low concentration of silver left in the fixer, the steel wool canister will enjoy an exceptionally long life.
All materials that may contact the fixer solution have passed exhaustive tests to prove their suitability. Only select plastics, graphite and type 316 stainless steel are used to fabricate such components.