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This paper takes the fine-grained hematite concentrate as the research object. In order to explore the serious overflow loss of the thickening tank in the actual production of thickening and dehydration, the average sedimentation velocity of the clarification layer interface, supernatant turbidity and the unit sedimentation area and other research indicators were used to investigate the effects of fine-grained hematite concentrate feed concentration, flocculant molecular weight, flocculant unit consumption, and flocculant solution concentration on the flocculation and sedimentation of fine-grained hematite concentrate. An experimental study on the influencing factors of flocculation and sedimentation of fine-grained hematite concentrate was designed by designing an orthogonal test. The test results were analyzed with the help of SPSS26 statistical software. The research results show that the order of the influence factors on the average settling velocity is: flocculant unit consumption > flocculant solution concentration > feed concentration > flocculant molecular weight; the order of influence on supernatant turbidity is: flocculant unit consumption > flocculant solution concentration > feed concentration > flocculant molecular weight; the order of the degree of influence on the unit settling area is: flocculant solution concentration > feed concentration > flocculant unit consumption > flocculant molecular weight. Considering comprehensively, the optimal conditions for the flocculation and sedimentation effect of fine-grained hematite concentrate in this experiment are: the molecular weight of the flocculant is 15 million, the feed concentration is 10%, the unit consumption of the flocculant is 60 g/t, and the concentration of the flocculant solution is 0.10%.

Calcium peroxide (CP) is an oxidizing agent that can gradually release hydrogen peroxide (HP) to achieve selective killing of cyanobacteria in water blooms, and reduce the phosphorus content in the water column. Despite the potential of CP for use in cyanobacterial water bloom disposal, there is a lack of research on the mechanism of oxidative damage on cyanobacterial cells by calcium peroxide. Further studies are required to comprehend the underlying scientific principles and potential risks and benefits of applying this approach to cyanobacteria disposal. In this investigation, we employed varying doses of CP for the treatment of Microcystis aeruginosa (M. aeruginosa), which resulted in the following findings: (1) the HP released from CP can damage the photosystem II of M. aeruginosa, reduce cell photosynthetic pigment content, intensify the degree of membrane lipid peroxidation, and increase the extracellular protein content; (2) CP significantly increased the soluble extracellular polysaccharide (sEPS) and bound extracellular polysaccharide (bEPS) content of cells (p

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In the future, the output of ultrafine full tailings will explode due to the massive mining of low-grade deposits and demand for the recovery of useful minerals. The best way to dispose of ultrafine full tailings is to prepare them into the paste for filling underground voids or surface stacking. The deep cone thickening of ultrafine full tailings is a key link of tailings paste disposal technology. In the thickening process of ultrafine full tailings, slow sedimentation velocity, high dosage of flocculant, excessive overflow turbidity, and low underflow concentration are the bottlenecks that restrict the application of disposal technology for ultrafine full tailings paste. To investigate the thickening characteristics of ultrafine full tailings, the sedimentation test in measuring cylinder, the small-scale and semi-industrial deep cone dynamic thickening tests were carried out. Results show that the nonionic flocculant with a molecular weight of 12 million is most beneficial for the settlement of the tailings. With increasing flocculant dosage, the turbidity of overflow decreases and underflow concentration remains unchanged. Upon increasing the solid flux, the turbidity of overflow increases and underflow concentration decreases. In particular, when the solid flux is 0.4 t·m−2·h−1, the feeding solid mass fraction is 12%, flocculant dosage is 50 g·t−1, and average solid mass fraction of the underflow of the small-scale and semi-industrial dynamic thickening test is 62.8% and 74.4%, respectively. Mud height has a significant influence on the underflow concentration. The solid mass fraction of the underflow of the deep cone thickener increases with the increasing mud height, and this process conforms to the DoseResp function. This growth process can be divided into three stages: (1) slow growth (mud height 1–4 m), (2) rapid growth (mud height 4–7 m), and (3) basic stable (mud height over 7–8 m). This is related to the compression performance of the tailings flocs at different mud heights. According to the function relation between the underflow concentration and mud height, the mud height can be adjusted to meet the required underflow concentration for underground backfilling.

The rapid settlement of tailings is an important technical guarantee for the continuous production of downhole filling. The selection of a reasonable flocculant is essential for accelerating the settlement speed of classified fine tailings. The present paper conducts indoor static sedimentation experiments, NMR observation, electron microscope scanning, and other methods to analyze the porosity and pore-size distribution characteristics of floc solution for classified fine tailing under four flocculants, namely, ZYZ, ZYD, JYC-1, and JYC-2. The dimension, spatial distribution characteristics, particle size characteristics, and morphological characteristics of the scanning electron microscope images of floc were studied. Results show that the unit consumption of flocculant at 30 g/t is the critical value for increasing the flocculation and sedimentation effect of the classified fine tailings solution. The highest distribution percentage of small-sized classified fine tailings and the lowest average pore size was observed under the ZYZ-type flocculant. This flocculant also obtained the lowest porosity, largest average floc size, largest area occupied by the floc, lowest pore percentage, and the densest floc structure. Thus, this flocculant showed the best flocculation effect. A negative correlation was observed between the equivalent diameter of floc with varying settlement heights. The dimension of floc increased with the decrease in bed settlement height, and the overall structure of the floc gradually transitioned from loose to dense from top to bottom. The present paper characterizes the microscopic morphology and spatial structure characteristics of floc under different flocculants from a microscopic point of view. The present paper also provides a scientific basis for the selection of the optimal flocculant. [ABSTRACT FROM AUTHOR]

Based on the low-concentration fine tailings obtained from the classification of certain gold ores in Shandong Province, the effective thickening of the tailings was carried out by flocculation and sedimentation process. The effect of flocculant dosage on the sedimentation characteristics of the fine tailings was investigated. At the same time, the pipeline transportation properties of cemented slurry of fine tailings with different concentrations were studied with the help of the Buckingham equation. Test results showed that the addition of flocculant significantly promoted the sedimentation of fine tailings. When the dosage of the flocculant was 60 g/t, the sedimentation rate of fine tailings reached 8.80 cm/min. The measurement of rheological parameters of cemented slurry and the calculation of pipeline transportation resistance provided an important basis for the concentration control of cemented slurry and its smooth transportation in the filling pipeline. [ABSTRACT FROM AUTHOR]

Calcium peroxide (CP) is an oxidizing agent that can gradually release hydrogen peroxide (HP) to achieve selective killing of cyanobacteria in water blooms, and reduce the phosphorus content in the water column. Despite the potential of CP for use in cyanobacterial water bloom disposal, there is a lack of research on the mechanism of oxidative damage on cyanobacterial cells by calcium peroxide. Further studies are required to comprehend the underlying scientific principles and potential risks and benefits of applying this approach to cyanobacteria disposal. In this investigation, we employed varying doses of CP for the treatment of Microcystis aeruginosa (M. aeruginosa), which resulted in the following findings: (1) the HP released from CP can damage the photosystem II of M. aeruginosa , reduce cell photosynthetic pigment content, intensify the degree of membrane lipid peroxidation, and increase the extracellular protein content; (2) CP significantly increased the soluble extracellular polysaccharide (sEPS) and bound extracellular polysaccharide (bEPS) content of cells (p < 0.05), causing the cells to exist as agglomerates and effectively allowing them to flocculate and precipitate, reducing the turbidity of the water body; (3) The increased dose elevated the pH and calcium ions significantly decreased the orthophosphate content, resulting in an increase in extracellular alkaline phosphatase activity, but possibly increasing the total extracellular nitrogen content. These results suggested that CP is an effective chemical algaecide for cyanobacteria, and has the potential to be applied to dispose of cyanobacterial blooms while reducing the phosphorus content of the water column and further inhibiting the growth and proliferation of cells. [Display omitted] • Simultaneous use of calcium peroxide achieves comprehensive eradication of Microcystis aeruginosa. • Calcium peroxide prompts increased extracellular polysaccharide secretion, enhancing aggregate sedimentation. • Calcium peroxide treatment influences orthophosphate concentrations, elevating pH, and reducing turbidity. • Calcium peroxide disrupts Microcystis aeruginosa cellular integrity, elevating alkaline phosphatase activity. [ABSTRACT FROM AUTHOR]

Removal of highly dispersed suspended solids (SS) from process water is critical for the sustainable production of iron ore dressing. However, it is difficult to handle high SS content process water that has multiple silicate components in a strongly dispersed system efficiently, using conventional flocculants alone. In this work, we compared the sedimentation performance and underlying mechanisms applicable when dosing suspended silicate minerals with different polyacrylamides (PAMs), and assessed the feasibility of a robust method using anionic PAM and calcium ions to remove SS. Preliminary analysis indicated that the main constituents of the SS were ultrafine quartz and chlorite particles, which severely interfered with separation behavior. Different PAMs exhibited diverse flocculation effects on chlorite and quartz, whereas only the combination of anionic PAM and calcium ions flocculated them effectively and simultaneously. Results from zeta potential and Fourier-transform infrared spectroscopy (FTIR) measurements suggested that flocculation was mainly affected by the affinity between the charges on the mineral surface and flocculant functional groups. Calcium ions acted as an activator for the adsorption of anionic PAM onto the quartz surface, through a chemical bridging effect. Response surface methodology (RSM), incorporating Box–Behnken design, was performed to explore the effects of reagent dosage and SS content on separation indices. Field application of this model in Sijiaying Iron Ore Mine, China, allowed optimal conditions to be established, which were 2.86 mg/L anionic PAM and 213 mg/L CaCl 2 , at pH 11. After applying these modifications, the quality of the process water became acceptable for long-term reuse, and higher grade (65.10%) and recovery (68.50%) were achieved. The proposed flocculation method and the main conclusions from our work can provide information and advice for similar low-grade iron ore mines. Image 1 • Chlorite and quartz are highly dispersed in iron ore dressing process water. • The flocculation behavior of different PAMs on chlorite and quartz was compared. • Only APAM + CaCl 2 can effectively flocculate both chlorite and quartz. • The influences of reagent dosage and SS content were evaluated using RSM. • The feasibility of the proposed method and model was verified by industrial tests. [ABSTRACT FROM AUTHOR]

Environmental issues associated with tailings management have made it the most daunting challenge faced by the mining industry. To dispose mineral tailings in a technical, environmental and economical way, the cemented paste backfill (CPB) technology is proposed and widely adopted. Here we summarize recent progress in CPB design, with particular emphasis on flocculation and sedimentation, CPB mix design and CPB pipe transport. We provide an updated picture of underlying mechanisms, experimental techniques, influencing factors and recent frontiers for each abovementioned process. The review concludes with some future directions for the field. We envisage a future in which the CPB design is optimised in an integrated CPB design system, accelerated by artificial intelligence and interpreted using atomic simulation. [ABSTRACT FROM AUTHOR]