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Slurries are produced in many industries as a by-product of an industrial process. Whilst these slurries vary in composition from industry to industry, they are often discarded as waste even though they contain components that could be recycled for use in the same process or separated and purified for use in other processes/products. To understand what the slurries contain, industry employs characterization techniques to see what the slurry is composed of. In this article we will look at why characterization of these slurries is beneficial and show some examples of where slurries have been reused because they could be effectively characterized.
Industrial Slurries and Their Characterization
Slurries come in two forms. The first, is that slurries can be formed as a convenient way of handling solids by pulverizing and mixing them with a liquid. This can be beneficial for material transportation. However, the second type of slurry is industrial waste and is produced by many processes across various chemical, oil and gas and manufacturing industries. The slurry is often a by-product of an industrial process of which most goes to waste. However, these slurries often contain a variety of materials, molecules and elements that can be beneficial for other processes, or in the manufacture of other products.
To find out what is beneficial within these slurries, industry needs to characterize them. The characterization and understanding of what is inside the slurry produced from their specific process can help to identify the ideal separation and purification processes needed to recover any valuable components. There are a wide range of characterization techniques available depending on what the slurry and potential components of interest are, but these can include spectroscopy and microscopy techniques, ultrasonic techniques, particle size distribution measurements, single particle measurements, pH measurements, colorimetry, acid digestion methods, titration, electrical conductivity measurements, statistical methods and elemental analysis methods (include heavy metal analyses).
In short, by characterizing slurries by various means, companies can determine whether the slurries contain any materials/molecules that may be of use. This means that many slurries that are produced during other processes can be reused, to not only minimize waste, but are also beneficial for producing an extra production stream (or income stream from the sale of purification of different components of the slurry).
Below we look at some examples of where certain elements of industrial slurries have been reused to create other materials, which were only possible because the slurries were effectively characterized.
Replacing Calcium Carbonate for Marble Slurries
Calcium carbonate is being increasingly used in many industries. Calcium carbonate is often mined from limestone rocks, but these rocks are finite and given how much industrial processes are increasing these days, a new way of reusing marble (crystallized calcium carbonate) as a substitute for “normal” calcium carbonate is a two-fold green process; it could help with the impact from over-mining and provides a reduction in waste.
One way of recovering calcium carbonate is from marble slurries. By chemically, physical, mineralogically and morphologically characterizing marble slurries, scientists have shown that marble can be used as a raw material with a very small amount of post-processing. By simply drying marble slurries and grinding up the marble into a powder, it has been found that the fine-powder marble can be used as an effective micronized calcium carbonate substitute in many applications.
Biosolids from Precast Concrete Slurries
The precast concrete industry generates a lot of concrete slurry waste when the mixer tanks are washed. Unfortunately, because of the high alkalinity (and therefore associated hazards), most companies dispose of it as waste into landfills. However, there is another option and scientists have been working on producing alkaline stabilized biosolids from these slurries.
The realization of biosolids from these slurries would not have been possible without a wide range of characterization methods, as this was the primary step in seeing whether biosolids were indeed feasible from such alkaline slurries. This recycling effort has various methods and can yield various biosolids (with differing levels of nutrients) for use as soil conditioner, top soil or fertilizers.
Sources:
- “Optical Characterization of Industrial Slurries”- Potenza M. et al, KONA Powder and Particle Journal, 2016, DOI: 10.14356/kona.2016016
- “Ultrasonic Characterization of Slurries in an Autoclave Reactor at Elevated Temperature”- Soong Y. et al, Industrial and Engineering Chemistry Research, 1996, DOI: 10.1021/ie950771p
- “Sludge Characterization of a Petrochemical Wastewater Treatment Plant, Iran”- Ahmadi M., Iranian Journal of Health Sciences¸ 2013, DOI: 10.18869/acadpub.jhs.1.2.10
- “CHARACTERIZATION OF DAIRY SLURRY IN SOUTHERN CHILE FARMS”- Salazar F. et al, AGRICULTURA TÉCNICA, 2007
- “Characteristics and disposal options of sludge from a steel mill wastewater treatment plant”- Ahmadi M. et al, Journal of Advances in Environmental Health Research¸ 2013, DOI: 10.22102/jaehr.2013.40132
- “Characterization methodology for re-using marble slurry in industrial applications”- Marras G. et al, Energy Procedia¸ 2017, DOI: 10.1016/j.egypro.2017.08.277
- “A novel slurry concept for the fabrication of lithium-ion battery electrodes with beneficial properties”- Bitsch B. et al, Journal of Power Sources, 2014, DOI: 10.1016/j.jpowsour.2014.04.115
- “Beneficial reuse of precast concrete industry sludge to produce alkaline stabilized biosolids”- Gowda C. et al, Water Science and Technology, 2008, DOI: 10.2166/wst.2008.011
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