Sources of sludge – that contain a variety of heavy metals – vary significantly and include a wide variety of metal plating & metal finishing operations and industrial waste treatment facilities. It is reassuring to know that the Micronics Engineered Filtration team has a great deal of applications expertise in working with industries that produce metal hydroxide sludge.
Let’s start with a little “simple” chemistry. When one adds caustic (sodium hydroxide) to water which contains dissolved metals, the metal reacts with the hydroxide ions to form metal hydroxide solids. For most metals, this reaction usually occurs when the pH is in the range of 9.0 to 9.5:
Metal + Hydroxides (from Caustic) → Metal Hydroxide Precipitates (Solids)
Examples of Metal Hydroxides include but are not limited to:
- Aluminum hydroxides
- Copper hydroxides
- Ferric hydroxides
- Magnesium hydroxides
- Nickel hydroxides
- Zinc hydroxides
When you are looking for durable, reliable, efficient & cost-effective filter press solutions for dewatering your metal hydroxide sludge or slurry, here are a few things to think about:
- All filter press cloth is not the same nor are all filter cloth vendors. Filter cloth selection for your metal hydroxide slurry is one of the keys to achieving top performance in your operation. Polypropylene (PP) filter cloth is often “spec’ed” for metal hydroxide sludge but what PP cloth? Let Micronics help you with proper cloth selection to get the best durability, cake release, and other performance factors. Talk to us about cloth selection and read this helpful blog post, “Is Polypropylene Filter Cloth Right for My Application?”
- Mixed pack membrane presses (also known as membrane squeeze or diaphragm squeeze) are often an excellent solution for providing top-notch dewatering performance with a reduced cycle time (since time is money!). Our filtration experts will be pleased to discuss whether a mixed pack press is right for your metal plating, electroplating, or industrial metal hydroxide sludge dewatering operation. Please take a look at this recent blog post on “Benefits of Mixed Pack Membrane Filter Plates.”
- Do I need to precondition with polymers to yield higher cake solids or shorten cycle time? The short answer is that it depends on the particular slurry and manufacturing process. Our filtration experts will work with you to determine if polymer addition is helpful to your particular process.
- You may be asking what filter cake solids you can expect. The filter cake solids achievable will vary significantly – ranging from ~25% up to 50-65% solid content – depending on the metal hydroxide. No two sludges are exactly alike.
Contact us for assistance with your metal hydroxide slurry dewatering needs. Micronics Engineered Filtration has the expertise for your demanding filtration applications.