Sludge Thickener

1. Definition and basic working principle of sludge thickener

Sludge thickener is a kind of thickening and clarifying equipment with central transmission structure and can work continuously or intermittently. It mainly targets sludge with a sludge concentration of 1% or less, improves its solid content (sludge concentration), and the outflow concentration after concentration is above 3%, which is convenient for subsequent mechanical dehydration and improves the working efficiency and use effect of mechanical dehydration.

Its working principle varies according to the type:

For some sludge thickeners, a vertical shaft is installed in the center of the thickening tank, which is driven to rotate by a motor fixed on the truss through a cylindrical gear reducer, an intermediate gear and a worm gear reducer. When working, there is a discharge hopper at the center of the bottom of the sludge thickener tank to discharge the concentrated product, and a circular overflow trough is provided around the upper part of the tank.

There are also sludge pre-thickeners. When the chemically conditioned sludge is evenly distributed on the circulating filter belt through a mechanical feed distributor, the flocculation effect of the sludge and the chemical agent causes the sludge water to be spontaneously released under the action of gravity. Under the bidirectional stirring action of the mud rake, the sludge flocs and particles shear and rub each other, causing the sludge structure to change, thereby promoting the release of sludge water, and the sludge is concentrated as the filter belt moves. The sludge water (filtrate) passes through the filter belt during the horizontal movement of the filter belt and is discharged, and the sludge is transported to the concentrated sludge collection system with the filter belt.

2. The main structure and component features of the sludge thickener

Central transmission sludge thickener:

Structural composition: It consists of five parts: thickening tank, specially designed large torque water-type bridge, main transmission mechanism, lifting mechanism, slag rake, etc. During the operation of the lifting mechanism and torque measurement switch protection device, if the thickener is overloaded, the lifting mechanism can lift the slag rake by stringing the vertical shaft to ensure the safe operation of the machine. Its main structure consists of two parts: a specially designed and manufactured torque measurement switch, an alarm, a control device and an actuator. It generally also includes a cake frame, a transmission device, a cake frame lifting device, a feeding device, a discharge device and a signal safety device.

Sludge pre-thickener:

Structural features: It is a screw press dehydrator. Its dewatering process includes the sludge in the sludge pool being transported to the metering tank through the sludge delivery pump to adjust the sludge intake; the sludge and flocculant are mixed in the flocculation mixing tank to form alum flowers; the alum flowers are concentrated by gravity in the concentration section, and the filtrate is discharged from the filter seam; the concentrated sludge continues to move forward along the direction of rotation of the spiral shaft and is fully dehydrated under the action of the back pressure plate; the dehydrated mud cake is discharged from the gap formed by the back pressure plate and the spiral body, etc. And the sludge processing volume and the moisture content of the mud cake can be adjusted by adjusting the rotation speed of the spiral shaft and the gap of the back pressure plate.

3. Types of sludge concentrators

According to the transmission mode:

Central transmission sludge concentrator: generally used as concentrate before filtration or for tailings dehydration. Suitable for concentrate concentration before filtration or other similar scenarios.

Peripheral transmission sludge concentrator: (The search results do not mention too many of its characteristics, which can be supplemented based on general knowledge. The bridge of the peripheral transmission concentrator rotates around the center of the pool, and the scraper scrapes the sludge to the central mud outlet, which is suitable for large-diameter concentrators, etc.). According to the working principle:

Gravity sludge thickener: relies on gravity to settle solid particles in sludge to achieve sludge concentration. For example, some common sludge thickening tanks equipped with simple sludge scraping devices belong to this category.

Centrifugal sludge thickener: The separation of materials using a centrifuge is carried out under completely closed conditions. For example, a horizontal screw centrifuge can generally separate, dehydrate, clarify and grade suspensions with a solid phase weight content of ≤10%, a liquid-solid volume concentration of ≤50%, a liquid-solid density difference of ≥0.05g/cm3, and an equivalent diameter of solid particles of ≥5μm.

Belt sludge thickener: The sludge is concentrated and dehydrated on the filter belt through gravity filtration, extrusion and other effects. For example, a belt filter press has an independent thickening section that can easily filter agglomerated sludge, greatly improving the processing capacity, with simple structure, simple operation and easy maintenance.

Stacked screw sludge thickener: suitable for dehydration of high and low concentration sludge, and can be widely used in municipal sewage treatment projects and water treatment systems in petrochemical, light industry and other industries.

4. Application fields of sludge concentrator

Sludge concentrator is mainly used in water treatment systems such as blast furnaces, continuous casting, hot rolling and water plants in the metallurgical industry, or for the concentration or purification of all solid slurries in industries such as coal, chemical, building materials, water sources, and sewage treatment. It can also be used for the concentration and dehydration of concentrate and tailings slurries in wet mineral processing operations. It is also widely used in municipal sewage treatment projects and water treatment systems in industrial industries such as petrochemicals, light industry, chemical fiber, papermaking, pharmaceuticals, and leather.

Sludge concentrator is a concentrating and clarifying equipment that is centrally driven in structure and can work continuously or intermittently. It mainly targets sludge with a sludge concentration of 1% or less, increases its solid content (sludge concentration), and the outflow concentration after concentration is above 3%, which is convenient for subsequent mechanical dehydration and improves the working efficiency and use effect of mechanical dehydration.