2. Curing Method
Curing method is to add curing agent to waste water-based drilling mud or drilling mud sediment, so that it can be converted into soil-like solid (pseudo soil) landfill in place or used as building material, etc. This method can greatly reduce the erosion of soil by metal ions and organic matter in waste drilling mud, thus reducing the environmental impact and harm of waste drilling mud, and at the same time can ensure that waste drilling mud pool can be ploughed back at the end of drilling process.
2.1 Cement curing technology: Cement curing is a treatment of cement as curing agent to solidify the waste slurry. Cement is an artificial inorganic cement material, the main components are SiO2、CaO、Al2O3 and Fe2O3.. There are many kinds of cement which can be used as curing treatment, the most common application is ordinary Portland cement. The curing principle is to form calcium silicate hydrate glue through silicate and water, and to form an object containing silicate fiber and hydroxide after solidification, to contain harmful substances, and gradually harden to form cement solidified body.
2.2 Lime curing technology: Lime curing is a method of curing waste slurry containing sulfate or sulfite with lime as main curing agent and active silicate as additive. The principle of lime curing is that in the presence of moisture, lime and silica-aluminate roots in additives react with the above type of waste mud, gradually coagulate, harden, and finally achieve curing.
2.3 Curing technology of fly ash: fly ash is a mixture of pozzolanic materials, mainly composed of potentially active impurities such as SiO2、Al2O3. The curing principle of fly ash is that, in the presence of water, silica and alumina are excited by alkaline substances in the mud to produce hydration hardening, stable hydration products (CSH and CAH,CAH) are generated by excitation, which will accelerate the reaction to form ettringite, further improve the gel composition and hardening quality of drilling waste mud system, and finally reach the curing target.
2.4 Water glass curing technology: Water glass is a soluble alkali metal silicate material made of alkali metal oxide and silica, which is a colorless and transparent viscous liquid. Water glass has hardening, binding, containment and other properties, can be used as cementitious materials. Water glass curing method is to use water glass as the main curing substrate, supplemented by inorganic acid substances (such as sulfuric acid, nitric acid and phosphoric acid), and then mixed with waste mud according to a certain proportion of ingredients, neutralization and condensation dehydration reaction, so that the harmful substances automatically dehydration, after condensation hardening, finally achieve curing.