What are the factors that affect Filter Press filtration?
The main factors affecting the dewatering efficiency of a filter press include
- Feed slurry solids percentage
- Slurry particle size distribution
- Chamber thickness
- Cake solids percentage
- Solid material permeability
What are the pump options for filter presses?
Pump options for filter presses include.
- A low-pressure centrifugal feed pump
- A high pressure centrifugal feed pump (two impellers on one shaft)
- Two centrifugal pumps in series, low pressure and booster pumps
- A single positive displacement pump
- Low-pressure centrifugal pump in parallel with a high-pressure positive displacement pump
How can filter presses reduce the operating costs of the entire plant?
The most frequent savings with filter presses are:
- Reduced waste volume and weight due to the production of drier, dewatered material, as well as reduced transportation, disposal and footprint costs.
- Reduction or elimination of chemicals used for dewatering compared to alternative technologies.
- Reduced labor through automation compared to alternative technologies.
- Higher value end products due to lower inherent moisture, or where additional drying by non-mechanical means (e.g., rotary dryers) is required, can significantly reduce BTU costs by reducing product moisture prior to drying.
Besides reducing operating costs, what other reasons would motivate a plant or mine to consider using a filter press?
Filter presses are often used to create a closed-loop process. This eliminates the need for settling ponds or tailings ponds, while also recovering process water for reuse. By eliminating the need for tailings ponds or settling ponds, valuable land reserves can be preserved or land freed up for mining rather than being covered with tailings.
In many cases, the use of a closed-loop process can also reduce regulatory permitting, while also sending a positive environmental message to investing companies.
Many companies now wait years to obtain a permit for a new settling pond, with no guarantee that the permit will be approved. Moving to a closed-loop process can eliminate some of these lengthy permitting processes.
As areas with large populations continue to grow, water availability and cost are becoming more of an issue. These areas also require quarried and mined materials, but the lack of water may limit consideration of new plants. A closed-loop approach using filter press wet treatment greatly increases the feasibility of a plant because the maximum recovery rate of recoverable water minimizes the need for new water sources.
What are the key options to consider when purchasing a filter press?
The most common options considered when purchasing a filter press are
Chamber thickness – The thickness of the chamber has a large impact on dewatering performance and should be selected through testing or experience with similar materials.
Concave chamber plate or membrane plate.
Feed Pressure– 125 to 225psi is the typical operating pressure for most high pressure filter presses equipped with modern filter plates.
Buffer or Storage Tank – Buffer tanks are typically used to allow filter presses operating in an intermittent process to be used in a continuous process. Buffer tanks of different sizes may be considered to ensure a smooth and controlled connection from the continuous process to the batch dewatering process.
Feed pumps – The feed pump is the heart of the filter press operation. Filter presses can be fed with centrifugal pumps, two-stage centrifugal pumps, volumetric pumps, diaphragm pumps, progressive cavity pumps or a combination of these pumps. Choosing the right pumping system is critical to performance and operating costs.
Blown core – This prevents slurry from being discharged with the filter cake and also reduces wear on the filter cloth and can improve the downstream process.
Open or closed filtrate drainage – Open filtrate drainage allows for easy identification of damaged filter cloths. This can greatly reduce filter plate wear.
The choice of filter cloth and the way the cloth is connected to the filter plate.
Automatic cleaning system – for cleaning filter cloths to reduce operator requirements and improve filtration performance when cloth clogging becomes a problem.