Treatment of tailings streams with one or more dosages of lime, and associated systems and methods

A method for treating tailings streams from oil sands, the method comprising:

• adding a first dosage of lime additive to a tailings stream to produce a first mixture, the first mixture having a pH less than about 12.0;
• combining the first mixture with a flocculant slurry comprising one or more polymers;
• separating the combined first mixture and flocculant slurry into a first stream and a second stream, the second stream having a pH of from about 9.0 to about 12.0;
• and
• adding a second dosage of lime additive to the second stream to produce a second mixture having a pH greater than 11.8 and a soluble calcium level of at least 93 mg/L, such that clay of the second mixture is chemically modified via pozzolanic reactions with the calcium cations.

A method for treating tailings from oil sands, comprising:

• adding a first dosage of lime to a tailings stream comprising bicarbonates, the first dosage of lime comprising soluble calcium cations;
• reacting the bicarbonates with the soluble calcium cations to produce a first mixture having a first soluble calcium level less than about 100 mg/L and a first pH of from about 9-12;
• and
• after adding the first dosage, adding a second dosage of lime to the first mixture having the first pH to produce a second mixture having a second pH greater than 11.8 and a second soluble calcium level of at least about 93 mg/L, such that clay of the second mixture is chemically modified via pozzolanic reactions with calcium cations.