Study On The Cemented Filling Of Gold Mine Tailings And Its Preparation Of Green Wall Material

Due to the low grade of gold ore,a large number of tailings will be produced during mining and dressing process,and the market demand for gold products will greatly increase the number of gold tailings undoubtedly.The piling up of a large number of gold mine tailings has caused serious harm to surrounding environment and occupied a large number of land resources.Therefore,it is extremely urgent to solve the problem of effective storage and disposal of gold mine tailings.It is of great significance to use slag-based cementing materials for downhole cemented filling of gold mine tailings and developing building wall materials.In this paper,gold mine tailings in Shandong province was taken as the research object,on the basis of basic tailings properties analysis,downhole cemented filling specimens and baking-free brick specimens were prepared by adding self-made slag-based cementing material,and the mechanic performance were studied.The solidification mechanism and microstructure of cemented filling specimens and baking-free brick specimens were analyzed systematically by means of X-ray diffraction analysis（XRD）and scanning electron microscopy（SEM）.The tailings cemented filling specimens were prepared by adding K₁ cementing material into the tailings slurry,and the properties of the cemented filling specimens were characterized.It was found that the fluidity of slurry can be improved by adding polycarboxylic acid water reducer,the slump of filling slurry was 278 mm when the mass content of water reducer was 0.15%.The compressive strength of cemented filling specimens was increased with the increase of cement/tailings ratio and tailings slurry concentration.Under the same experimental conditions,the 28 d compressive strength of cemented filling specimens was 3.8⁴.9 times higher than that of P.O 42.5 cement.The softening coefficient of cemented filling specimens was increased with the increase of cement/tailings ratio,and the range was 0.83⁰.92.The shrinkage rate of cemented filling specimens was decreased with the increase of cement/tailings ratio,and its shrinkage rate was in the range from 0.54%to 0.70%.The influence of tailings particle size distribution on the mechanical properties of tailings cemented filling specimens was as follows:The compressive strength of the full tailings cemented filling specimens was the highest,followed by the fine tailings cemented filling specimens,and the compressive strength of the coarse tailings cemented filling specimens was the lowest.The tailings cemented filling specimens were prepared by adding K₂ cementing material into the tailings slurry,and the properties of the cemented filling specimens were characterized.It was found that the compressive strength of cemented filling specimens was increased with the increase of cement/tailings ratio and tailings slurry concentration.Under the same experimental conditions,the 28 d compressive strength of cemented filling specimens was 2.0³.0 times higher than that of P.O 52.5 cement.The softening coefficient of cemented filling specimens was increased with the increase of cement/tailings ratio,and the range was 0.81⁰.89.The shrinkage rate of cemented filling specimens was decreased with the increase of cement/tailings ratio,and its shrinkage rate was in the range from0.60%to 0.80%.It was feasible to use desulfurized ash to replace sulfate raw materials,and the compressive strength of cemented filling specimens could meet the requirement of filling structural strength.The tailings baking-free brick specimens were prepared by adding K₁ cementing material into tailings sand,and the properties of the baking-free brick specimens were characterized.It was found that with the increase of mixing water consumption,the compressive strength of baking-free brick specimens was increased first and then decreased.the compressive strength of baking-free brick specimens was the highest when mixing water consumption was 10%,the 28 d compressive strength was 15.15 MPa.The compressive strength of baking-free brick specimens was increased with the increase of cement/tailings ratio,but its water absorption was decreased with the increase of cement/tailings ratio,and its water absorption rate was in the range from 11.3%to 13.6%.The compressive strength of baking-free brick specimens was decreased with the increase of times of freeze-thaw cycle,the decrease in compressive strength of the baking-free brick specimens was gradually reduced after 15 times of freeze-thaw cycle.The compressive strength of baking-free brick specimens was decreased with the increase of times of dry-wet cycle and the compressive strength of baking-free brick specimens was remained stable after 7 times of dry-wet cycle.