Powdered glass cullet is a material in both strong supply and demand. A product of post consumer glass cullet, powdered glass cullet has many uses, as an abrasive, as a cement compound, as an aggregate, as a polozzanic strengthening agent, as a filtration agent, as sand for golf courses or sports turfs, the list goes on. Powdered glass cullet is an exceptionally versatile material with good strength and low chemical reactivity.
From Silica To Cullet
Powdered glass cullet is made from ground recycled glass, which begins life as virgin glass, a product made primarily from silica sand with certain additives combined with it to lower the melting point and increase chemical resistance. There are a variety of types of glass available on the market, but the most common glass in circulation today, and the type most often found in glass cullet form, is soda-lime glass. This type of glass contains between 70 to 74 percent silica, and is the glass from which most all bottles and jars are made.
Soda lime glass is made by preparing a batch of raw materials including silica, lime, soda, alumina, and iron oxide if the glass is to be green or amber according to a predetermined formula, and melting the mixture at very high temperatures, usually in gas fired furnaces. The relative quantities of the various raw materials differ according to the intended use for the glass. There are two main type of soda lime glass, the first of which is known as float glass, which is formed by a float process into sheets of glass, and the second of which is known as container glass, which is blown and pressed into the desired container shape. Container glass makes up the bulk of glass cullet, as most glass cullet comes from bottles and jars deposited at recycling stations, or put out for collection at kerbside pickup points.
Once the glass mixture is melted down, it is then stirred thoroughly. It is important in order for the glass to have a uniform strength and composition that the melted glass is homogeneous. After the homogenization process is complete, the glass mixture is then refined to remove unwanted bubbles which could cause structural defects and manufacturing faults later on. Sodium sulfate and sodium chloride are both fining agents added to the mixture that aid in the removal of unwanted gas bubbles.
The glass is then formed into plates or containers, and goes out into the world where it performs its function, and is subsequently returned for recycling, usually shattered into many pieces and mixed in with other glasses, plastics, and other contaminants.
This is raw glass cullet, and in order to be transformed into useful, clean, powdered glass cullet it must undergo benefication, a process whereby the contaminants are carefully removed using a combination of magnets, metal detectors, washes, human picking stations, and a process known as fine sizing.
Fine sizing is a process whereby the glass cullet is gradually ground down into finer and finer particles, and passed through a series of increasingly fine screens. As this process is taking place, ceramics and other harder compounds are not worn down as quickly as the glass, and so are left behind on the screens. The resulting product is clean, contaminant free, fine powdered glass cullet, ready to be used in a wide range of applications.
Powdered Cullet Applications
Filtration Systems
For many years, water filtration systems made use of silica sand as a filtration agent, but it has since been discovered that powdered glass cullet can be even more effective than silica sand, and is sometimes less expensive to obtain. The main advantage of powdered glass cullet over silica sand, cost aside, is the fact that glass cullet does not allow harmful bacteria and deposits to adhere to the powdered particles, which means that the resulting water is cleaner, the overall life of the filtration system is longer, and the sand does not need to be replaced nearly as often.
Septic Treatment Systems
Because powdered glass does not retain microbes and bacteria the way natural sand does, powdered glass is also being used in some septic filtration applications. The structure and nature of powdered glass cullet is perfectly suited to filtering out impurities from septic sources, far better than more traditional mediums.
Filler Aggregate In Concrete
Powdered glass has proved to be a useful filler aggregate in concrete applications. The pozzolanic nature of glass (a term which describes its reaction with lime which results in strengthened compounds) makes for a stronger aggregate, and the powdered form of the glass makes for nice dense particle packing. When powdered glass cullet is used as an aggregate, less drying shrinkage is observed, and there is also increased elasticity. Powdered glass cullet makes a highly resistant and strong aggregate, it is not temperature sensitive, and has very good freeze/thaw resistance not to mention excellent resistance to abrasion.
Fluxing Agent
Powdered glass cullet makes an excellent fluxing agent for a wide range of applications. When used as a fluxing agent in brick manufacturing, the firing temperature of the bricks can be reduced by a hundred degrees. This sort of temperature reduction represents significant savings in energy and production costs, not to mention wear and tear on the ovens. Powdered glass has also been found to be an effective fluxing agent in the ceramics industry, and in the metal industry.
Blasting Abrasives
Powdered glass is highly abrasive, and is starting to replace traditional blasting media as the preferred choice. Sand blasting is a common method for removal of paints, lichens and other substances from walls, floors, and other surfaces, and at one time silica sand was the media of choice for this application. Powdered glass has several advantages over silica sand however, for starters it is denser than many other types of blasting abrasive, and provides far more particles per pound. This means faster and better cleaning. Another major advantage of powdered glass cullet is the fact that it contains hardly any (less than one percent) crystalline silica, a compound which causes a serious lung disease in humans, and which is prevalent in silica sand.
Ceramics
As was briefly mentioned above, powdered glass can function as a fluxing agent in the production of ceramic items. Powdered glass also has other applications in the ceramic world, as an additive and as a means of ornamentation. Powdered glass is often combined with ceramics to create lightweight ceramics, or can also be sprinkled, or combined with a gloss to provide a shiny or sparkly finish on some ceramic items.
Purchasing Powdered Glass Cullet
Powdered glass can be one of the ’safest’ forms of glass cullet to purchase as the fine sizing process removes a great deal of the contaminants that larger forms of glass cullet may possibly still contain. However, not all powdered glass has been fine sized, in many cases it may simply have been ground down from raw cullet, and if this is the case, it may still contain contaminants. Whilst one of the most versatile and potentially cleanest forms of glass cullet, powdered glass cullet is only as good as the benefication process it underwent before being ground into a fine powder.
A rule of thumb when investigating powdered glass cullet is to inquire as to the methods of benefication that were employed during recycling, and to obtain a sample of the product, and perhaps even references from other customers before committing to a larger purchase. Whilst this might sound overly picky, powdered glass containing contaminants, especially ceramic contaminants, may lack necessary strength, chemical resistance, or react badly with other materials.
Powdered Glass Cullet Supplier
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