Abstract: Methods and systems for storing and mineralizing carbon dioxide in soil are disclosed herein. In some embodiments, the method comprises adding lime and carbon dioxide to a soil column including soil to form treated soil. After adding the lime and carbon dioxide, the method also includes strengthening the treated soil in the soil column by mineralizing the lime and carbon dioxide in the soil column. The method can further include adding a binder to the soil column and mixing the binder with the soil, lime, and carbon dioxide. The binder can include, for example, pozzolan, cement, cementitious material, and/or a manufactured calcium carbonate product.

Abstract: A composition configured to be mixed with cement, and associated systems and methods are disclosed herein. In some embodiments, the composition includes at least 10% by weight lime particles, and at least 35% by weight pozzolan particles. Properties of the composition can include a magnesium oxide concentration of at least 0.5%, and an iron oxide concentration of at least 0.5-2.0%, an aluminum oxide concentration of 2-8%, a silicon dioxide concentration of 20-40%, a potassium oxide concentration of 20,000-30,000 ppm, and a sodium oxide concentration of 10,000-20,000 ppm. In some embodiments, the lime-based cement extender composition, or product, is combined with cement to produce a cement blend for use in the mining industry as mine backfill.

Abstract: A lime-based cement extender composition, and associated systems and methods are disclosed herein. In some embodiments, the lime-based cement extender composition includes 5-20% by weight lime particles, 40-50% by weight limestone particles, and 40-50% by weight pozzolan particles. Additionally or alternatively, the lime-based cement extender composition can comprise a calcium oxide concentration of 45-65%, a magnesium oxide concentration of 0.5-2%, an iron oxide concentration of 0.5-2.0%, an aluminum oxide concentration of 2-8%, a silicon dioxide concentration of 20-40%, a potassium oxide concentration of 20,000-30,000 ppm, and a sodium oxide concentration of 10,000-20,000 ppm. In some embodiments, the lime-based cement extender composition, or product, is combined with cement to produce a cement blend for use in the mining industry as mine backfill.

Abstract: Methods and systems for treating tailings at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises (i) providing a tailings stream comprising bicarbonates and a pH less than 9.0, (ii) adding a coagulant comprising calcium hydroxide to the tailings stream to form a mixture having a pH of at least 11.5 and a soluble calcium level no more than 800 mg/L, and (iii) dewatering the mixture to produce a product having a solids content of at least 40% by weight. In some embodiments, the pH and soluble calcium level of the mixture cause chemical modification of clay materials of the mixture via pozzolanic reactions. In some embodiments, the undrained shear strength of the product increases over a period of time of at least two days.

Abstract: Methods and systems for calcining dewatered tailings and/or mine waste are disclosed herein. In some embodiments, the method comprises (i) processing dewatered tailings comprising clay minerals, (ii) calcining the processed tailings to produced calcined tailings, and (iii) altering a composition and/or one or more characteristics of the calcined tailings to produce a cementitious product. Altering the composition can include blending the calcined tailings with one or more additives, such as lime, dolomitic lime, lime kiln dust, argillaceous limestone, limestone, pulverized quicklime, ground calcium carbonate, quicklime, gypsum, natural pozzolans, artificial pozzolans, water, flow aids, or the like.

Abstract: Methods and systems for treating tailings at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises (i) providing a tailings stream comprising bicarbonates and a pH less than 9.0, (ii) adding a coagulant comprising calcium hydroxide to the tailings stream to form a mixture having a pH of at least 11.5 and a soluble calcium level no more than 800 mg/L, and (iii) dewatering the mixture to produce a product having a solids content of at least 40% by weight. In some embodiments, the pH and soluble calcium level of the mixture cause chemical modification of clay materials of the mixture via pozzolanic reactions. In some embodiments, the undrained shear strength of the product increases over a period of time of at least two days.

Abstract: Methods and systems for treating oil sands tailings streams using multiple dosages of lime are disclosed herein. In some embodiments, the method comprises providing a tailings stream including 3-40% solids by total weight, combining the tailings stream with a first dosage of lime to produce a first mixture having a pH of less than 12.0, and then combining the first mixture with a polymer to produce a second mixture. In some embodiments, the method can further include combining the second mixture with a second dosage of lime to produce a third mixture having a pH greater than 12.0, and dewatering the third mixture in a centrifuge unit and/or a pressure filtration unit to produce a product stream having 55% or more solids by weight.

Abstract: Methods and systems for treating oil sands tailings streams at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises providing a tailings stream including 10-55% solids by total weight, increasing the pH of the tailings stream by combining the tailings stream with lime to produce a lime-tailings mixture having a pH of at least 11.0, and dewatering the lime-tailings mixture to produce a first stream having 10% or less solids by total weight and a second stream having 50% or more solids by total weight. The first stream can correspond to a release water stream, and the second stream can correspond to a cake. The lime slurry can include about 10% lime by total weight, and can comprise lime hydrate, quicklime, or a combination thereof. Dewatering the lime-tailings mixture can include routing the lime-tailings mixture to a centrifuge unit and/or a pressure or vacuum filtration unit.

Abstract: Methods and systems for reducing greenhouse gas emissions from sediments containing organic materials via treatment with lime are disclosed herein. In some embodiments, the method comprises (i) providing sediments comprising a first pH less than 10.0, fermentable organic materials, and microbes configured to produce carbon dioxide and/or methane via degradation of the organic material; (ii) adding a coagulant comprising lime to the sediment to produce a mixture comprising a second pH of at least 11.0 and excess soluble calcium ions; and (iii) after adding the coagulant, forming a buffer comprising soluble sodium and calcium bicarbonates within the mixture by enabling the excess soluble sodium and calcium ions to react with carbon dioxide. Forming the buffer can comprise decreasing the pH of the mixture from the second pH to a third pH of 8.0 or greater.

Abstract: Methods and systems for treating oil sands tailings streams at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises providing a tailings stream including 10-55% solids by total weight, increasing the pH of the tailings stream by combining the tailings stream with lime to produce a lime-tailings mixture having a pH of at least 11.0, and dewatering the lime-tailings mixture to produce a first stream having 10% or less solids by total weight and a second stream having 50% or more solids by total weight. The first stream can correspond to a release water stream, and the second stream can correspond to a cake. The lime slurry can include about 10% lime by total weight, and can comprise lime hydrate, quicklime, or a combination thereof. Dewatering the lime-tailings mixture can include routing the lime-tailings mixture to a centrifuge unit and/or a pressure or vacuum filtration unit.

Abstract: Methods and systems for treating oil sands tailings streams using multiple dosages of lime are disclosed herein. In some embodiments, the method comprises providing a tailings stream including 3-40% solids by total weight, combining the tailings stream with a first dosage of lime to produce a first mixture having a pH of less than 12.0, and then combining the first mixture with a polymer to produce a second mixture. In some embodiments, the method can further include combining the second mixture with a second dosage of lime to produce a third mixture having a pH greater than 12.0, and dewatering the third mixture in a centrifuge unit and/or a pressure filtration unit to produce a product stream having 55% or more solids by weight.

Abstract: Methods and systems for treating oil sands tailings streams at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises providing a tailings stream including 10-55% solids by total weight, increasing the pH of the tailings stream by combining the tailings stream with lime to produce a lime-tailings mixture having a pH of at least 11.0, and dewatering the lime-tailings mixture to produce a first stream having 10% or less solids by total weight and a second stream having 50% or more solids by total weight. The first stream can correspond to a release water stream, and the second stream can correspond to a cake. The lime slurry can include about 10% lime by total weight, and can comprise lime hydrate, quicklime, or a combination thereof. Dewatering the lime-tailings mixture can include routing the lime-tailings mixture to a centrifuge unit and/or a pressure or vacuum filtration unit.