1. The Skid - Remco ion exchange and deionization systems are assembled on a fiberglass skid fabricated by Remco Engineering and bonded with structural epoxy. The skid is coated with a chemical resistant epoxy. Single skids up to 10' X 12' are used for 90 gpm systems or smaller. Larger systems use multiple skids.

2. The Buffer Tank - Mounted on the skid is the main buffer tank which is sized for a 20 minute retention time. Our buffer tanks are constructed of fiberglass using isopthalic ester resin with a vinyl ester resin interior gel coat (100 mils thick). Each fiberglass tank has either a full or half hinged lid. The main level controls, diverter valve assembly, air agitation assembly and all of the feed lines are mounted on the lid.

3. pH Control System - Remco Engineering supplies a dual high/low pH adjust system. Both a pump bypass to the main buffer tank and an air agitation system mix the solution entering the tank. pH adjust additions are injected in the return line to the pH adjust tank to insure rapid mixing. Oversized metering pumps insure rapid adjustment to 0.2 pH. The pH control systems are enclosed in a Nema 4x housing keeping in line with our basic policy of utilizing corrosion resistant construction materials. To decrease wear on the controller relays, separate replaceable relays operate the metering pumps. Interlocks are provided to the main program controller to insure no solution flows when the system is out of the desired pH range.

4. Pumping system - Dual centrifugal pumps are used to provide a backup and keep downtime to a minimum. The pumps are mounted on the skid and controlled from the main electrical control panel with an A/B switch. Each pump has it own motor contactor. The pumps have their own circuit on a separate circuit breaker in the main panel. One of the pumps is on all of the time. When solution is not being feed through the resin columns, the solution is recirculated back to the pH adjust tank to increase the mixing efficiency. The recirculation loop is controlled by both the pH controller as described above and by the level control. The level control is a three probe conductivity type system working in a pump-down mode. The system is set up so approximately 15-20% of the solution is left in the tank as a recirculation buffer. When the solution is raised to the upper level probe, the system starts the pump down mode that continues until the low level probe is reached or the pH is out of the set point range for the pH controller.

5. The diverter valve assembly - We use modular construction techniques as much as we can to insure that we can build and sell our systems at a reasonable cost. Our diverter valve (valve stack) assembly is a good illustration of this philosophy. Most of the valves to control the flow through the system are assembled in one unit that is mounted in the skid just before the interconnecting plumbing is started. The valves are air operated so it takes little time to hook up the air lines and it is easy to check and see if they are operational.

6. Media filter - Each system has an oversized media filter constructed of thermo-wound fiberglass with a rating of at least twice the nominal flow rate. The media filter is large enough and fine enough to catch any material which could plug the resin columns. There is a manually initiated, timed backwash function which cleans the filter in about 10 minutes. The backwashed material is captured in a bag filter constructed of stainless steel. The media filter is activated by a pushbutton on the main control panel and the time for backwashing is controlled by the main programmable controller. Dual filter configurations are automatically controlled by the microprocessor controller on a timed cycle. The manual backwash initiation is still available but not normally needed.

7. Ion exchange columns. - Our columns are constructed of fiberglass on systems up to 80 gpm. We use a lead/lag system where the lead (first) column is regenerated when it is full of metal and the lag (second) column is used exclusively during regeneration and becomes the lead column after regeneration. The system stays on line during the regeneration phase. At least half of the systems resin is always on stream. The system is designed for one gallon per minute per cubic foot of resin. This is a conservative design flow rate. Even when operating on only one half of the systems' resin during the regeneration cycle, the effluent metal levels are very low. Copper systems usually run under 0.5 ppm and can run under 0.05 ppm, depending on how full the columns get between regenerations and how closely the system is monitored.

8. Ion exchange resins - Many different resins are available from many different manufacturers. There is no such thing as a metal specific resin although many are better for some metals than others. We use resins that maximize the efficiency of the system for the particular metal of interest. Please seek a quotation if you wish a better definition of a resin for your particular situation.

9. Control System - Our system uses a microprocessor to control the valves and interlocks. The control system is mounted in a Nema 4x fiberglass enclosure. We feature all air operated valves controlled by manifolded solenoid valves mounted in the main control panel. The main control panel also houses the level control board, circuit breakers, power latching relay, and all motor controllers. Our system features fully automatic and manual control of the regeneration cycle. Optional systems can fully automate the process where an operator is called if needed. Our systems are computer capable featuring RS232 porting.

10. Regeneration - Regeneration is initiated with one button as is backwashing the media filter. Once the regenerant tanks are full, select either backwash column A or column B with the front pushbutton and then let the system work. Three to four hours later, depending on the system capacity, the system automatically returns to the correct state. One column is always on line during regeneration. No further operator intervention is required. After regeneration, a valve is opened and the regenerant pump is turned on from the main control panel; the regenerant tank is emptied to the reclaim module for metal reclamation. When the metal is plated out to a low level, the recovered acid is pumped back into the regeneration tank from the control panel of the reclaim module. See our Metal Recover Ion Exchange Process literature for details on the chemistry of MRIX systems or the Deionization literature for details on the DI process in general .

11. Regeneration Modules - Regeneration modules consist of a tank for regenerant, a centrifugal pump, diverter valves for draining and cleaning, and a manual override on the main control panels. There are usually two regeneration modules on larger systems, smaller systems use an eductor for caustic which is fed from a 55 gallon drum. One is for the acid regenerant which recovers cation metals, the other is for caustic which prepares the resin for the next cycle. Our regenerant tanks are constructed of polypropylene and reinforced where necessary. Each is sized to handle the proper concentration and amount of regenerant. No molded polyethylene tanks are ever used . Regenerant recovery is important to us so our systems are designed to remove as much undiluted regenerant as possible before rinsing the system. Our resin columns are "blown down" with air before and after each rinse to increase the effectiveness of each step in the process and to minimize water usage. Our acid regeneration modules fill up to within 1/4" of the initial level after the regenerant is recovered. To reclaim a regenerant, it is pumped to a recovery module where the metals are plated out.

12. Recovery Modules - Each recovery module consists of a tank constructed of polypropylene with appropriate girthing. Each unit is self contained and mounted on a separate skid. The units include the main tank sized at 2 times the volume of the regeneration module on the main skid, a recirculation pump, motor controller with housing, and a electrolytic cell. Each cell has multiple anodes on close centers for high transfer efficiencies. Low current densities allow efficient plating down to reasonably low metal levels. Each electrowinning cell has between 18 to 44 square feet of cathode area available. Multiple cell systems are available. The same units can be used for cyanide destruct or for electroless recovery or chelate destruct. Rectifiers supplied with self contained recovery units are mounted on the same skid.