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The ion exchange technology comprises of two components - ion exchange materials (resins) and processes. The information about the resins is given in the IX resins section. Below are basic types of the IX processes described.

 

The ion exchange process includes three major stages: sorption of valuable or unwanted ions, desorption (or elution) and washing. An addition stage - regeneration - could be used in case when the IX resin needs to change a from after elution. The operation of the ion exchange processes can be conducted in either cyclic (batch) or continuous mode. The cyclic operation assumes that the IX resin stays in the same equipent and all stages follow one after another. In the continuous mode each stage is conducted in a separate, dedicated vessel, and the resin is moved between the reactors or columns by small portions. However, from the point of view of imput and output flows both cyclic and continuous processes may look as continuous.

     Continuous Ion Exchange (CIX)

The continuous ion exchange (CIX) technology is designed for sorption of valuable elements or removal of impurities from water and solutions. The process is realiased in column type of equipment and includes three stages sorption, desorption and washing. In some cases the neutralisation column is used where the resin is neutralised or converted to a required form to be used in the sorption process. The basic process flow diagram is shown in picture on the left.

In each column the resin moves counter-currently to the solutions. The resin flow between columns is shown in the diagram by dashed brownarrows. The physical transportation of the resin through the process is realised by a pneumatic system from the bottom of the column to the top of the next one. The resin saturated with valuable ions in the sorption column is stripped in the desorption column. Then it is washed and returned into the sorption column.

     Resin in pulp (RIP) technology

Originally the proposed RIP/ IX technology was developed in 1950s for the uranium industry. It became the first really continuous extraction process. Nowadays, the technology is utilised in uranium and gold industries and in the recovery of their by-products. The RIP/ IX plants process millions tons of minerals a year.

The essence of the resin in pulp (RIP) technology is a selective extraction of metals, such as uranium, gold, nickel, molybdenum, copper, rare earth elements, from viscous solutions and pulps. The RIP process can be used to process pulps with the solids content up to 50%.

Picture shows the process flow diagram adapted for metal recovery from milled ore or tailings. The ion exchange plant consists of two circuits - sorption and desorption circuits. The sorption process is combined with the leaching process and realised in several RIP reactors. The reactors operate in a pseudo-continuous counter-current mode. The pulp is fed into the reactor 1 and the resin into the last reactor. The pulp and resin are moved from one reactor into another in the counter current manner. The barren pulp goes to the waste dam and clear water is returned into the pulp preparation tank.

The fully loaded resin from the RIP circuit is transferred into the desorption circuit to produce concentrated solution of a target metal (45-50 g/L). The desorbed (regenerated) resin returns into the RIP circuit.

 

      NEW! Resin in moisturised mix (RIMM) technology

The RIMM process delivers high metal recovery at a reduced consumption of leaching agents. It is ecologically friendly due to lower residual levels of target metals and leaching agents in the waste. It has been tested in several applications including low grade ore, tailings and with different metals like copper, cobalt and nickel. The RIMM process is a patented technology jointly developed and owned by InnovEco and Oryxeio.

The RIMM process could be very simple and consists of the following steps: blending in wet solids, sorption leaching in moisturised mix (i.e. RIMM), dilution (with separation of resin from pulp), and elution (or desorption). The eluted copper may be recovered by a traditional process such as electrowinning (EW) or crystallisation. The corresponding process flow diagram is shown in Picture.

Depending on the type of minerals, content of the target metal and other factors, the process diagram may be modified. For example, a scavenging stage may be added to recover leaching agents (e.g. when dealing with ammonia). This provides significant flexibility for the RIMM process and makes it possible to use this process for the metal recovery from various minerals and metal bearing materials.

 

     Cyclic Ion Exchange

Ion exchange operated in a cyclic mode is traditionally used in water purification and related industries. Those applications include softening, dealkalisation and decontamination, as well as water preparation for many industries such as food and beverage, power generation, chemical and petrochemical, electronic and semiconductor. Among other applications the cyclic ion exchange is widely used in biotechnology, pharmaceutical, organic synthesis, sugar and sweeteners, wineries and breweries.

Since all cycles (sorption, desorption and washing) are carried out in the same vessel, two or more vessels are needed to work in parallel. As shown in picture one reactor could process contaminated water, while desorption and regeneration cycles are conducted in the other one.

 

     ADVANTAGES OF RIP/ CIX

The resin in pulp (RIP) technology is an advanced hydrometallurgical process which meets the three criteria - high efficiency, being environmental friendly and complex approach to mineral processing.

The major advantage of the resin in pulp (RIP) process is the integration of leaching and sorption processes. It enables the increase in the metal extraction rate, reduction of the residence time, decrease of water consumption, minimisation of environmental impact.

Economics

In comparison with the conventional technologies the RIP/ CIX implementation allowes increasing the metals extraction by 5-10%, cutting the energy consumption by 2-3 times, increasing production productivity by 3-4 times, and significantly reducing consumption of acid, filtering materials and other consumables.

Environment

The RIP/ IX process has also a number of ecological and environmental advantages. A positive impact can be demonstrated by the following examples. The proposed IX plant has a small footprint in comparison with the traditional technologies. As shown in picture below the RIP/ IX plant takes only 5-10% (red rectangle) of the footprints of vat leaching / CCD plants. This significantly reduces the environmental impact on the ground. It means that when the plant is closed due to the resources exhaustion, the IX plant would require much less finance for the area rehabilitation approximately 10-20 times less than for the traditional plants.


In summary the low environmental impact of the IX technology is determined by the following factors:
- low chemicals consumption (mostly stoichiometric to the produced copper quantity)
- rather high pH level of the wastes (usually pH3.5 that requires just minimum pH adjustment for disposal in the nature)
- absence of dangerous consumables (in contrast to solvent extraction which utilises organic solvents)
- low water consumption (5-10 times less than in heap leaching)
- low energy consumption due to usage of air assisted stirring and resin transferring
- small footprint and therefore low impact on the ground

Complex mineral processing

The RIP/ CIX technology enagles effective recovery and separation of various metals. It can be utilised to process polymetalic deposits or produce accompanying metals as by-products of main metal. It can be applied to a variety of metals, inlcuding base metals, radioactive metals, rare and rare earth elements and precious metals.

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