Water Treatment & Solid / Liquid Separation
Quadra offers a range of range of flocculants and coagulants which are used extensively whenever the extraction process uses water or lixiviants to aid mineral and metal recovery.
Water Treatment and Heavy Metals
Why precipitate heavy metals?
High concentrations of heavy metals are usually toxic to fauna and flora. Accordingly, environmental regulations are put in place to limit their concentration in wastewater. Precipitation processes are characterized by the capability to remove metals from solution metals that are in excess concentration down to their solubility limit for the present solution conditions.
What heavy metals are commonly targeted for precipitation?
- Arsenic (As)
- Cadmium (Cd)
- Copper (Cu)
- Lead (Pb)
- Mercury (Hg)
- Nickel (Ni)
- Silver (Ag)
- Tin (Sn)
- Zinc (Zn)
How to precipitate heavy metals chemically?
Depending on the targeted heavy metals, inorganic coagulants such as aluminium sulphate (alum), ferric salts (sulphate or chloride), calcium hydroxide (lime), as well as organic coagulants such as PolyDadmac (diallyl dimethyl ammonium chloride), PolyAmine (epichlorohydrin dimethylamine) and cationic flocculants will work by reducing the zeta potential of the colloidal system to a value sufficiently low for the colloidal particles to be destabilised and coalesce.
Anionic or non-ionic flocculants supplied by BASF can then be used to bring together smaller particles or aggregates into much larger aggregated particles that will settle faster and produce a less turbid effluent.
What if this is not enough?
While most of the heavy metals will be captured in larger aggregated particles, the heavy metal concentration present in solution in the wastewater may still be above the authorized limit.
In these cases, the addition of TMT 15® (trimercapto-s-triazine) supplied by EVONIK can precipitate heavy metals by creating a heavy metals complex particle bounding which can then be easily separated by using a clarifier or filter press. The chemical solubility characteristics of the pollutants to be removed will impact the optimum process pH.
What are the benefits of using TMT 15®?
- Effective over a wide pH range
- Ready to use solution
- Nonhazardous substances
- Easy to integrate into existing wastewater treatment plants
- Avoids expensive secondary treatments
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Coagulants & Flocculants are used to improve the rate of solid / liquid separation in an aqueous slurry i.e. to destabilise the slurry so that the solids settle or can be filtered more easily. Bringing together small particles or aggregates into much larger aggregations using long chain molecules which bridge between particles and bind them into a macro-structure (floc).
Why use coagulants?
To promote the natural aggregation of fine particles during inter-particle collisions by enhancing the attractive forces between particles.
What types of coagulants are available?
There are a great number of coagulants available in the market.
Typically, the coagulants are divided into two families. In water treatment, the most common family are “Inorganic”. The Inorganic coagulants include aluminum salts, iron salts, bentonite, lime, etc.
The other type of coagulants are the organic coagulants. These include Poly; DADMACs, Polyamines, Polyacrylate ester, formaldehyde-amine resins. Blended Organic-Inorganic coagulants are also available in the market. The functionality depends on the process needs.
It is important to understand that the selection of a coagulant is based on which substance needs to be removed from the liquid. Also, what the overall effect of adding a coagulant may have on the rest of the process and the environment
How does aggregation of solids work?
Aggregation of the solids through flocculation leads to increased permeability of the solids fraction in relation to the water phase.
Sedimentation – increase settlement rate
Filtration – increase rate of water release
Applications: clarification, centrifuges, thickeners, organic binders, filter presses, drilling mud, run off streams, geo bags, vacuum drum, tailings, tailings dust suppressant, mineral recovery, arsenic treatment.
To bring together small particles or aggregates into much larger aggregations using long chain molecules which bridge between particles and bind them into a macro-structure (floc). According to “Stokes” law, flocculants increase the rate at which water can be separated from solids.
Dry Flocculants versus Liquid Emulsions?
The decision of whether to use a dry flocculant versus a liquid goes back to the 1970s. Dry flocculants as the name implies are made in dry form and are shipped in dry form. They have between 5 – 10 % moisture and are considered the most active form of flocculant per kilo received.
Liquid flocculants were developed in order to address feeding challenges that the dry flocculants were known for in the same era. Liquid flocculants are shipped in liquid form and are generally in the range of 25%-35% active.
Quadra exclusively represents the BASF portfolio of mining solutions products in Canada and Alaska. BASF’s Mining Solutions business offers a diverse range of mineral processing chemicals and technologies to improve process efficiencies and support the economic extraction of valuable resources.
Magnafloc®: Standard anionic, non-ionic & cationic flocculants:
In thickeners and clarifiers, the products are designed to enhance settling rates, improve clarities and reduce underflow volumes. When used in filtration processes, Magnafloc® reagents increase filtration rates and yields, as well as reducing cake moisture contents.
Rheomax® DR High performance flocculant:
Our advanced the range of flocculants create a high density and more robust aggregate compared to conventional products, which are effective on a wide variety of mineral one types. This change in aggregate shape allows for faster consolidation, high underflow densities and low underflow yield stress.
Rheomax® DR advanced flocculants have demonstrated benefits to solid / liquid separation processes by enabling improvements to be made to thickener throughout, underflow density and yield stress.
Rheomax® ETD Tailings Management:
Enhanced Tailings Disposal is a method of Tailings Management in which novel technology is used to change and control the structural and drainage properties of mineral processing residues. Tailings thickeners generate high-density underflows with high yield stress, which are often pumped long distances to a final tailings impoundment area. The tailings are then deposited, dried and eventually rehabilitated.
The Rheomax® ETD process can rigidify tailings at the point of disposal by initiating instantaneous water release from the treated slurry. This accelerates the drying time of the tailings, results in a smaller tailings footprint and allows the released water to be returned to the process faster.
At the core of BASF’s offering is an extensive range of LIX oxime extractants and amine extractants that are widely used in the purification of copper, uranium, nickel, vanadium, molybdenum, germanium, palladium, rare earths and other precious metals from leach solutions.
LIX solvent extractants are recognized throughout the copper industry as the go to reagent for copper recovery. BASF’s broad range includes aldoxime and ketoxime extractants and incorporates blends formulated to specific customer needs / operational challenges. Our range of solvent extraction reagents are produced at our state of art facility in Cork, Ireland. These water insoluble oximes, in a high flash point hydrocarbon diluent, form water insoluble complexes with various metallic cations.