Purification and recovery plants

Another area in which Blue Water Technology believes a lot is the recovery of raw materials, not only in terms of economic savings for customer companies but also from a perspective of sustainability, that is to reduce the amount of pollutants discharged.

In decorative chromium plating processes, as in most non-thick galvanic processes, the largest amount of chromic acid is discharged into the wash water: the chromium deposited on the workpiece is only 5-6% of the chromic acid used. In addition to the waste of raw material, this results in the consumption of chemical reagents and increased sludge production in the water treatment plant.

Through an appropriate number of static washes and the installation of resin plants for the purification of the recovered chromium bath, using a vacuum evaporator it is possible to obtain a concentrate that can be used to replenish the bath. This technology allows a recovery of at least 90% of the chromium acid  currently consumed.

The recovery of the washing solutions after nickel plating takes place through selective membrane filtration plants. If properly dimensioned, these plants reduce by more than 90% the consumption of nickel sulphate and nickel chloride salts added periodically to the electrolytic deposition baths. Due to the nature of the deposit, this technique is most widely used in high drag productions such as barrel.

The purifying filters most used are listed below.

Nickel-plated baths purification plant

Nickel baths are subject to pollution by foreign metals, mainly iron, copper and zinc (the latter present when galvanizing pieces in zama). This pollution of the nickel-plating bath causes defects in deposit deposition, especially in surface areas subjected to lower stresses.

Our water purification plants retain foreign heavy metals by continuously purifying the nickel-plating bath: once the exchange capacity has been exhausted, the resin must be regenerated to regain its exchange capacity.

Plant purification baths of chromium trivalent (CR III) 

Trivalent chromium-based deposition baths are now increasingly used due to environmental restrictions, due to market needs due to the increasingly pressing demand to reduce the use of hexavalent chromium (Cr VI), and for greater resistance of the deposits obtained with these electrochemical baths to certain salt corrosion tests.

However, one of the major difficulties in managing these deposition baths is their sensitivity to small traces of metallic pollutants, mainly iron and copper. Blue Water Technology designs and produces specific filtration systems capable of retaining the foreign heavy metals of trivalent chromate baths.

Purification plant for passivation baths with chromium III

Trivalent chromium-based passivation is one of the most common post-galvanizing treatments aimed at improving the resistance of the galvanized material. However, due to the pollution caused by a partial melting of zinc or by washing water with a low exchange rate, the amount of metallic zinc tends to increase until it decreases the resistance of the galvanized parts to salt spray tests. In these cases the only solution is to replace partially or totally the passivation bath. 

In addition to an investment for the reformulation of the bath, this procedure creates an environmental problem for the disposal of the waste solution. Through special resins, it is possible to selectively and continuously remove the zinc inside the bathroom: in this way an optimal quality of the bathroom will always be guaranteed.

One of the areas of greatest use of demineralization plants to recirculation  is the galvanic industry and surface treatment, in which large volumes of water are normally used for the washing of the parts to be treated. These waters contain concentrations of pollutants  which require water purification before they can be discharged.

In order to reduce water consumption and limit the use of chemicals and the production of waste sludge, recirculating water demineralisation plants are used.

The recirculating demineralisation plant  consists of a pressurisation pump, a mechanical and/or adsorbent filter and an ion exchange resin demineralizer. The ion-exchange resins  will treat the ions by returning demineralized water and must be regenerated with acid and soda once saturated, that is to say at an exhausted duty cycle. The regeneration process produces  a concentrated liquid rich in pollutants that must be disposed of at external Alternatively, it can be combined with the other unrecirculated washing waters after batch precipitationtreatment and sent to the chemical-physical purification plant.