POTASSIUM SILICATES
What exactly is Potassium Silicates?
Well, Potassium silicate glass is a colourless, super cooled melt of potassium carbonate and pure silica sand with the general formula K2SiO3. Potassium silicate solutions are prepared by dissolving potassium silicate glass in hot water. This results in a viscous fluid that has a density of in the region of 1.3 to 1.4.
The ratio of the SiO2: K2O can also be manipulated depending on the application. Mass ratios of between 1.4:1 and 2.2:1 are typical.
Potassium silicates is one of the most commonly used chemical products in the world. The Potassium silicate “boom” started in the 19th century, when ground-breaking applications in detergents, adhesives and refractory paints were developed. Its applications have been diversified into many different fields. This includes detergents, paper, construction, paints, water treatment, industrial products and raw materials.
When handling Potassium silicate – one must do so with care. It is advised that chemical safety goggles and rubber gloves must be worn as it has a high PH. See the MSDS for the methods of use that is available as free download at the end of this blog!
USES AND APPLICATIONS OF POTASSIUM SILICATES
Fertilizer
Potassium silicates serve as fertilizers for use in turf and crop applications as a source of soluble potassium and silicon. Other benefits include:
• Improves photosynthesis
• Reduces the negative effects of excess aluminium, sodium and manganese.
• Improves plant growth, improving yield and quality.
• Enhances reproduction by improving pollination and increasing pollen fertility.
• Produces an amour-like layer in the outer cell wall resulting in stronger, more resilient plants.
• Pest resistance as it strengthens the plants cell walls.– can increase the yield in sugar cane farming up to 30 %, due to this ability.
Potassium Silicates
Welding Rods
Potassium silicate is specifically recommended as a binder for consumable electrodes (“stick rods”) which are used with alternating current welding machines. Along with good binding properties, potassium silicate serves as a fluxing component and produces a steady hot arc, with lower arc voltage than sodium silicate, which tends to sputter or extinguish. Higher tensile strength and less elongation of weld metal can be obtained. Potassium silicate finds use as a binder in welding rods for mild steel, low-hydrogen steels, and stainless steel.
Electronic Applications
Potassium silicate is almost universally used to settle and bind phosphorus to the face of black and white television picture tubes, and also in colour projection TV tubes.
These phosphor screens are prepared by mixing the phosphor with an electronics grade potassium silicate solution and introducing this mixture into a clean tube filled with a dilute electrolyte solution such as strontium silicate. A gel forms around the individual phosphor particles, which then settle to the bottom of the tube. The strength of the phosphor-to-glass bond is a function of the concentrations of silica, potassium oxide, and electrolyte, as well as of trace irons, water purity, settling time and temperature. Compatibility is excellent with the wide range of phosphors. Uniform films are obtained in contrast to sodium silicate, which binds in an erratic, uneven manner.
Cleaning Compounds and Corrosion
Inhibition
Potassium silicate enhances the wetting and cleaning properties of soaps and detergents. Liquid cleaners that show excellent storage stability can be formulated with potassium silicate. In addition, the silicate ion has marked anticorrosion properties to protect metal surfaces, and potassium silicate can be effective as a corrosion inhibitor in other applications as well.
Catalyst Support
Silica supports for catalysts can be prepared with potassium silicate or sodium silicate via formation of a gel with acid. Catalyst preparation typically requires prior analysis of many processing variables; the choice between potassium silicate and sodium silicate will depend on the nature of the catalyst desired, and on the comparison between the effects of the respective cations, K+ or Na+, on the finished product.
Mortars
Potassium silicate solutions show a high value-in-use as a binder in mortars which must withstand acidic conditions other than hydrofluoric acid. In particular, potassium silicate should be considered where sodium silicate in mortars shows limited durability. Mortars prepared with potassium silicate show less tendency than sodium silicate mortars to stick to the trowel and have more “body” (thixotropic) to hold bricks in place before setting permanently. Mortars containing potassium silicate also withstand higher temperatures. This favours its use in refractory cement. Silicate mortars also show excellent acid resistance.
Oil-Gas Drilling
Potassium silicate based drilling fluids provide oil-like shale stability, low depletion rates, corrosion control, and improved cementing. It can be seen as an environmentally acceptable alternative to oil-based drilling fluids.
Coatings
Since potassium silicate films resist “bloom” or efflorescence (crystalline deposit on surfaces), it is useful as a pigment vehicle for brick, concrete, and stone. Silicates are also used in hardening and dustproofing concrete. A siliceous deposit closes the pores to make the concrete surface less permeable to oils and other liquids, and can also act as an “anti-dusting” compound. The non-blooming characteristic of potassium silicate also accounts for its excellent performance as a binder in roofing granules.
For more information regarding potassium silicate and its uses and applications, contact Sun Silicates (Pty) Ltd.
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