The present disclosure is directed towards a soil additive for sequestering carbon dioxide. The soil additive comprises particles of set concrete, wherein the particles of set concrete have not fully cured.

A method of this disclosure directionally drills at least one well extending from ground surface to an interior of an underground mine located below ground, the well being at an oblique angle relative to vertical; blends or mixes together a hazardous material, like lead, zinc, arsenic, and cadmium with cement including a plasticizer; pumps or flows the mixture into the well, wherein the mixture flows toward a lower end of the mine and hardens in place. The method allows for the permanent placement of contaminated mixtures like chat into mines or shafts or depositories, as defined by the United States Environmental Protection Agency, CERCLA and Superfund laws and complies with rules for the permanent closing of these structures with contaminated material and contaminated substances.

Provided is a calcium carbonate generation method and system in which calcium carbonate having a high purity can be generated using a calcium-containing waste. Provided is a calcium carbonate generation method of generating calcium carbonate from a calcium-containing waste, the calcium carbonate generation method including: a calcium dissolution step of adding aqueous hydrochloric acid to a calcium-containing waste and dissolving calcium to generate an aqueous solution containing a calcium ion; a separation step of adjusting a hydrogen ion concentration index of the aqueous solution containing a calcium ion and separating a component containing at least one selected from the group consisting of Si, Al, Mg, and heavy metal from the aqueous solution; and a calcium carbonate collection step of generating calcium carbonate using an aqueous solution obtained in the separation step and an aqueous solution containing potassium carbonate and/or sodium carbonate.

A production method of carbon dioxide fixing sludge fine powder as a low-carbon binder. Water is added to residual concrete or returned concrete to form it into a slurry, gravel and sand are separated and removed therefrom, fine sand is separated and removed from the sludge water by a wet cyclone to obtain concentrated sludge water, and the concentrated sludge water is dehydrated to obtain a sludge cake. The sludge cake is put into a rotary drum, hot air and highly concentrated carbon dioxide are supplied into the rotary drum, the carbon dioxide is fixed and is crushed and dried to obtain carbon dioxide fixing sludge fine powder. Alternatively, the sludge cake is crushed and fractured to obtain sludge fine powder. This sludge fine powder is exposed to highly concentrated carbon dioxide to obtain carbon dioxide fixing sludge fine powder.

A method for simultaneously drying and carbonating a mineral waste material that includes carbonatable calcium and/or magnesium compounds and/or silicate, aluminate or silicate-aluminate phases in a spray dryer, wherein a starting material slurry is provided including the mineral waste material in the form of particles with a D90500 m and at least 30 wt.-% water, a hot gas is provided including at least 4 Vol.-% CO.sub.2 and fed into the spray dryer, the starting material slurry is sprayed into the hot gas in the spray dryer wherein a temperature of 100 C. and a relative humidity of <50% are adjusted in the spray dryer, the starting material slurry is transformed into evaporated water and a dry, carbonated product comprising calcium carbonate and/or one of silica gel or alumina gel or silica-alumina gel, and the dry, carbonated product is separated from the gas and evaporated water.

A storage and processing tank having a jet line with injection nozzles, agitators, and a fluid supply line, is used to maintain cement waste in an injectable form prior to injecting the materials into a subterranean formation for disposal.