A new process that converts sediment, brines and industrial wastes into usable, construction-grade cement that can be sold on the open market. Organic waste products are burned off during processing. Heavy metals are sequestered in the cement product. The new process addresses both of the primary environmental concerns associated with recycling waste reject brines and dredge sediments.
A mixture of waste sediment and proprietary modifiers (used in cement manufacturing) is melted at 1200–1400 °C or higher. These temperatures destroy organic materials such as dioxins, PCBs, and pesticides. The process yields carbon dioxide, water, and hydrogen chloride gas, which can easily be removed by injecting powdered lime or by installing a calcium oxide filter. The system produces no environmental waste of its own.
The melted material, “Ecomelt”, resembles lava, is quenched to form a solid that can be pulverized or drawn into μm-sized fibers for later use. Heavy-metal contaminants remain, but they do not leach from the resulting cement, leaving them permanently stored. The concentration of heavy metals in the cement product is comparable to that for commercial portland cement (the gray or white structural or decorative cement most commonly used in the U.S.).
Cement-Lock plants are simpler and cheaper to maintain than existing portland cement manufacturing plants. Portland cement manufacturing requires raising the temperature to more than 1500 °C to form the final product, making it necessary to implement complex energy management strategies to reduce costs. Moreover, in contrast with conventional incinerators, the new process does not produce high levels of nitrous oxides or ash that may leach heavy metals and must be disposed of as hazardous waste.