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Clarometer liquid sampling system cuts flocculant usage

Clarometer is a liquid sampling system used in mining and mineral applica tions to automatically control flocculant chemical usage. It does this by repeatedly drawing a sample from the centre well of a thickener into a clear acrylic cylinder.

The sample is analysed in relation to a set of predetermined parameters to automatically adjust the chemical dosing. This results in a considerable reduction of flocculant usage and hence substantial cost savings.

Flocculants are a family of chemicals used in many industrial water treatment process applications, such as coal, gold, iron ore, nickel and mineral sands, to improve sedimentation and hence water recovery. Their use in CCD (Counter Circuit Distillation) circuits in gold and alumina processes apply the same prin ciple for different recovery requirements.

The Clarometer has developed into a family of products to accommodate a variety of different applications and requirements. The two basic versions are the FAS (Flocc Addition System) and the PE (Photo Electric Clarometer).

Thickener bridge

The FAS uses a turbidity optical sensor to determine the settling rate and has the capacity to control both anionic and cationic flocculant. The PE Clarometer is a very basic unit and uses a simple PE cell to determine settling rate. The PE Clarometer only controls a single anionic flocculant pump.

The Clarometer is physically located on the thickener bridge, and so is in an ideal location to gather a variety of thickener process information. The TTC (Total Thickener Control) Clarometer, has been developed with this in mind.

The TTC has the capacity to control the under flow pumps using flow and density, plus bed level control, in addition to the normal settling time control. It has many other control features. It uses an Ethernet remote screen as an operator interface in the plant control room. Another very versatile unit is the UFC (Universal Flocc Controller). This Clarometer has all the features of the FAS plus another unit called the STM as well as the bed level features developed for the TTC Clarometer.

The company recently installed four of these in a goldmine in Indonesia. This application was able to capitalise on all the standard features of the UFC Clarometer, including dual language operator screens. There are many harsh mineral applications, of which alumina is the most severe. This CCD process uses sodium hydroxide (caustic) at 105°C. Oscillation has developed two products for this and other similarly harsh applications.

The first is the HTA (High Temperature Applications) Clarometer. This unit has an innovative sampling technique to obtain a sample using positive pressure and so maintain the integrity of the hot sample for analysis. This system is currently being patented.

Bed level monitoring

A second product for these applications is the VBI (Virtual Bed Interface), a bed level monitoring system, which works on the diver principle. The VBI has a cable drum to raise and lower the high temperature probe, a separate control panel with operator touch screen and an independent cleaning station for automatic cleaning.

Oscillation has created a special turbidity probe for this system. As well as solving many technical issues which were specifically related to this application, the materials used to manufacture the VBI required considerable research.

The VBI combined with the HTA Clarometer enables Oscillation to provide a unique control solution for these harsh environments.

Australian engineering company, Oscillation, has been designing and manufacturing Clarometer sampling systems for over 25 years.

The Clarometer is recognised both in Australia and internationally as a leading device in this field, and Oscillation has several patents to support its designs.

[Colin Howard is the Manager at Oscillation Pty Ltd.]

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