The Control System of Sludge Thickening Tank Design

The automatic control system of underflow ore discharge of thickening tank and automatic control system of flocculant addition plays an important role in practical application. In the following, the application of automatic control of underflow ore discharge and control of flocculant addition is introduced in combination with the actual situation, which has played a good role in field application.

Thickener is one of the large-scale process equipment commonly used in mining and metallurgical industries. The function of the thickener is to separate the slurry from solid and liquid, so as to achieve the purpose of obtaining its overflow supernatant or underflow concentrated ore slurry. High-efficiency thickeners are widely used due to their small footprint, low energy consumption, and high efficiency. Among them, the automatic control of underflow ore discharge and the automatic control of flocculant addition is very important.

1. Automatic control of underflow ore discharge in thickener

The thickener underflow control system achieves the purpose of changing the underflow discharge speed by controlling the underflow variable frequency slurry pump speed. The higher the rotating speed of the slurry pump, the larger the amount of ore discharged and the shorter the time of slurry settling. The lower the rotating speed, the smaller the amount of ore discharged and the longer the time of slurry settling, and the concentration gradually increases.

The core of the bottom flow control of this project: according to to basically the same amount of feed dry ore and discharge dry ore, the underflow discharge flow is deduced. Through the PID control operation of the set value and the measured value of the discharge flow, the speed of the variable frequency slurry pump for the underflow discharge of the thickener is controlled, and the automatic control of the underflow discharge of the thickener is realized.

2. Flocculant addition automatic control system

In order to improve the slurry sedimentation effect of the high-efficiency thickener, the addition of flocculants is used to promote the slurry sedimentation in practical applications. After the pulp is mixed with the flocculant, it enters the thickener through the central vertical cylinder. The deflector at the outlet end of the feeding vertical cylinder forces the ore slurry to spread around in the horizontal direction to avoid impacting the sediment layer, and the large flocculated particles settle down, and the liquid rises through the sediment layer. The sediment layer has a filtering effect, so that the particles cannot rise with the liquid, so as to achieve the purpose of solid-liquid separation. Adding too little flocculant will affect the thickening efficiency, and adding too much will cause the flocculation material to loosen and reduce the compressibility of the solid particle layer during the compression period.