Title: Preparation of Glass-Ceramics via Cosintering and Solidification of Hazardous Waste Incineration Residue and Chromium-Containing Sludge
Authors: Huirong Lin, Pengpeng Zhang, Linghao Zeng, Binquan Jiao,* YanChyuan Shiau,* and Dongwei Li*
Link: https://pubs.acs.org/doi/10.1021/acsomega.1c01659?ref=pdf
Hazardous waste is a commonly generated side product from many chemical and industrial processes, and safely managing this waste is crucial. One method of handling hazardous waste is incineration. however the residue (hazardous waste incineration residue, or HWIR) needs to be handled and disposed of properly also, as the hazardous materials may still be present. Jiao et al. examined a particular type of hazardous waste created by the electroplating industry, chromium-containing sludge (CCS), which can contain heavy metals such as chromium, lead, and copper. These metals can cause environmental damage if they enter the ecosystem. They specifically looked at a disposal method for HWIR that will sequester it and produce a useful byproduct: construction materials. Other research has established that solid wastes such as slags and ashes from industrial processes such as blast furnace operation can be solidified into glass-ceramics, inorganic materials that have a mixture of glass and ceramic properties. Glass-ceramics are stable enough that the waste used in their creation poses no direct threat to the environment, and could conceivably be formed into bricks to create new buildings. Jiao et al. realized that CCS contains all of the necessary metal oxides that are required to cause the formation of glass-ceramics, and so CCS that has been turned into HWIR is a potential way to both dispose of a waste product and create something of value at the same time.
Jiao et al. created their first glass-ceramic by drying, grinding, and sieving the base HWIR, melting it into a glass at 1450 °C, and again drying, grinding, and sieving the glass. They then heated the sintered glass again, to a lower temperature to initiate nucleation, and then to a higher temperature to initiate crystallization, and created their glass-ceramics. They varied the nucleation temperature and time and the crystallization temperature and time to optimize their glass-ceramics for the highest strength that they could achieve. They also created glass-ceramics using a combination of the HWIR glass and the dried and ground CCS.
The group determined that the optimal conditions for producing the strongest glass-ceramic from HWIR is a nucleation temperature of 760 °C, nucleation time of 1.5 hours, crystallization temperature of 1060 °C, and crystallization time of 1 hour. The resulting glass-ceramic had a compressive strength of 258.73 MPa, which is significantly more than the 10-20 MPa compressive strength of standard bricks.
The combination HWIR CCS glass-ceramics were less strong, however. Containing 10% CCS dropped the compressive strength of a sample to 115.79 MPa, and 50% CCS samples had a compressive strength of 89.56 MPa, which, while much lower, still meets the requirement of 10 MPa for construction materials.
However, while the exclusively HWIR sample had effectively no leaching of chromium, copper, or lead, the HWIR CCS samples had leaching. Specifically, samples stayed below EPA limits for copper and chromium at 20 and 30% CCS. But when the CCS content was just 10%, the lead leaching concentration exceeded EPA limits, with the amount increasing as the CCS concentration increased. It is implied in the paper that this was not a big issue however, due to how the crystal lattice formed and solidified. Unfortunately, there is no explanation of how they came to this conclusion.
In conclusion, Jiao et al. created a new method for reprocessing a type of industrial waste, CCS, into a useful product, glass-ceramic. This will hopefully lead to an overall reduction in the amount of CCS waste that needs to be treated via other less efficient methods in the industrial world, and reduce the amount of heavy metal waste that will need to be remediated in the future.
Title: Preparation of Glass-Ceramics via Cosintering and Solidification of Hazardous Waste Incineration Residue and Chromium-Containing Sludge
Authors: Huirong Lin, Pengpeng Zhang, Linghao Zeng, Binquan Jiao,* YanChyuan Shiau,* and Dongwei Li*
Link: https://pubs.acs.org/doi/10.1021/acsomega.1c01659?ref=pdf
Hazardous waste is a commonly generated side product from many chemical and industrial processes, and safely managing this waste is crucial. One method of handling hazardous waste is incineration. however the residue (hazardous waste incineration residue, or HWIR) needs to be handled and disposed of properly also, as the hazardous materials may still be present. Jiao et al. examined a particular type of hazardous waste created by the electroplating industry, chromium-containing sludge (CCS), which can contain heavy metals such as chromium, lead, and copper. These metals can cause environmental damage if they enter the ecosystem. They specifically looked at a disposal method for HWIR that will sequester it and produce a useful byproduct: construction materials. Other research has established that solid wastes such as slags and ashes from industrial processes such as blast furnace operation can be solidified into glass-ceramics, inorganic materials that have a mixture of glass and ceramic properties. Glass-ceramics are stable enough that the waste used in their creation poses no direct threat to the environment, and could conceivably be formed into bricks to create new buildings. Jiao et al. realized that CCS contains all of the necessary metal oxides that are required to cause the formation of glass-ceramics, and so CCS that has been turned into HWIR is a potential way to both dispose of a waste product and create something of value at the same time.
Jiao et al. created their first glass-ceramic by drying, grinding, and sieving the base HWIR, melting it into a glass at 1450 °C, and again drying, grinding, and sieving the glass. They then heated the sintered glass again, to a lower temperature to initiate nucleation, and then to a higher temperature to initiate crystallization, and created their glass-ceramics. They varied the nucleation temperature and time and the crystallization temperature and time to optimize their glass-ceramics for the highest strength that they could achieve. They also created glass-ceramics using a combination of the HWIR glass and the dried and ground CCS.
The group determined that the optimal conditions for producing the strongest glass-ceramic from HWIR is a nucleation temperature of 760 °C, nucleation time of 1.5 hours, crystallization temperature of 1060 °C, and crystallization time of 1 hour. The resulting glass-ceramic had a compressive strength of 258.73 MPa, which is significantly more than the 10-20 MPa compressive strength of standard bricks.
The combination HWIR CCS glass-ceramics were less strong, however. Containing 10% CCS dropped the compressive strength of a sample to 115.79 MPa, and 50% CCS samples had a compressive strength of 89.56 MPa, which, while much lower, still meets the requirement of 10 MPa for construction materials.
However, while the exclusively HWIR sample had effectively no leaching of chromium, copper, or lead, the HWIR CCS samples had leaching. Specifically, samples stayed below EPA limits for copper and chromium at 20 and 30% CCS. But when the CCS content was just 10%, the lead leaching concentration exceeded EPA limits, with the amount increasing as the CCS concentration increased. It is implied in the paper that this was not a big issue however, due to how the crystal lattice formed and solidified. Unfortunately, there is no explanation of how they came to this conclusion.
In conclusion, Jiao et al. created a new method for reprocessing a type of industrial waste, CCS, into a useful product, glass-ceramic. This will hopefully lead to an overall reduction in the amount of CCS waste that needs to be treated via other less efficient methods in the industrial world, and reduce the amount of heavy metal waste that will need to be remediated in the future.
“BRICKS” by marc falardeau is licensed under CC BY 2.0
