Recovery of unburned carbon from lime calcination process using statistical technique

In this study, unburned carbon recovery from lime calcination plant tailings was investigated using diesel oil, kerosene, MIBC and pine oil. A series of laboratory experiments using 2³ full factorial designs was conducted to determine the types and dosages of collector and frother. For these tests, data were analyzed by the paired t-test. The main and interaction effects on combustible recovery were evaluated using Yates' analysis. By optimizing the flotation parameters at slurry concentration of 34% solids, flotation time of 2.5 min, pH of 7.5, collector diesel oil dosage of 2780 g/t, and frother pine oil dosage of 2620 g/t, unburned carbon (UC) has been successfully recovered with 93.07% combustible recovery (CR) and 6030 kcal/kg calorifical value.     

The Influence of Reagent Dosage on the Floatability of Pyrite During Coal Flotation

Abstract

In general, as the quantity of frother and/or coal collector is increased, so too, does the flotation of the undesired pyrite. The problem is particularly serious with oily reagents. For some coals, however, a collector, such as fuel oil, is required to achieve a high coal recovery. This requires a compromise between the competing desires of a high coal recovery and a high pyrite rejection. This study gives the quantitative effect of reagent dosage on coal and pyrite floatability and details several means of minimizing pyrite floatability during coal flotation. The effect of fuel oil on coal flotation is especially interesting in that the flotation process changes from froth flotation to emulsion or agglomerative flotation as the amount of oil is increased. This phenomenon provides an additional method of rejecting pyritic sulfur.     

Oil shale beneficiation by froth flotation

It was found that froth flotation is capable of upgrading oil shale to improve the oil yield in the Fischer assay from 0.117 to 0.175 1/kg at 75% organic recovery in 50% of the rock. Feed particle size affected the float yield and grade and thus the separation efficiency. For economic reasons, grinding to very small particle sizes was avoided. With moderate grinding, particles < 75 μm required less frother and collector to float than particles ? 150 μm and the selectivity was lower for < 75 μm particles. The best separation efficiency was achieved at a feed particle size of 500-150 μm. As the quantities of frother and collector increased, both the float yield and the percentage organic recovery increased, but the percentage mineral rejection decreased. As a result, the separation efficiency reached a maximum at float yields of 40–50%. The types of frother and collector affected the float yield. However, they had no significant effect on the grade of float if the amounts of frother and collector were controlled to achieve the same float yields.     

Flotation response of coal washery reject fines: Characteristics,process optimization,and oxidation

The present paper outlines the characterization, electrokinetic behaviour, and flotation response of rejected coking coal fines with 32.5% ash generated in a coal washery in Eastern India. The response methodology and central composite rotatable design (RSM-CCRD) were used for the process modelling and optimization of the flotation process using diesel, methyl isobutyl carbinol (MIBC), and sodium hexametaphosphate as a collector, frother, and depressant to maximize ash reduction, yield, and combustible recovery. At optimum condition, a 9.7% clean ash coal was achieved with a 63% yield at collector, frother, and depressant dosages of 0.78, 0.31, and 0.80 kg/ton, respectively. The model prediction and experimental data corroborated sufficiently. Subsequently, within 1 year, the fines oxidized and did not float with the collector. Fourier-transform infrared spectroscopy (FTIR) confirmed surface oxidation on oxidized coal. The oxidized coal responded favourably to acid oil, a vegetable oil refinery waste. With acid oil as a collector, the oxidized coal can upgrade to 12% clean ash coal with a 60% yield; the combustible recovered is 80%. The work indicates successful upgradation of fresh and oxidized coal using the froth flotation process.     

The effect of different flotation operating parameters on the froth properties and their relation to clean coal ash content

Froth properties and their relation to the concentrate grade play an important role in monitoring flotation running conditions and predicting flotation concentrate quality. In this paper, the correlation between the froth properties and clean coal ash content was investigated under complicated conditions where the frother dosage, gas velocity, and froth height were changed together. For the froth properties under study, their degree of correlation with clean coal ash content decreased in the order of homogeneity, water recovery, gray value, and froth velocity. The coefficient of determination (R²) of the fitting relationship between homogeneity and clean coal ash content was as high as 0.9028, because homogeneity has a close correlation with the foam structure and foam destabilization behaviors.     

Froth stability and entrainment evaluation of a novel frother for KCl/NaCl flotation

The rate of KCl recovery by froth flotation using low-grade carnallite is 70%–85%. Herein, a novel frother, dipropylene glycol butyl ether (DPNB), was prepared to increase the flotation efficiency of KCl recovery systems. DPNB could be applied at only half the dosage of the conventional frother methyl isobutyl carbinol (MIBC) and achieve a KCl recovery rate of 94.8%–98.6% with a high KCl grade (63.2%–66.5%). To date, these results are the best reported for pneumatic flotation. DPNB had a 10% higher maximum dynamic stability factor compared with MIBC; moreover, the apparent entrainment velocity of DPNB was half that of MIBC. The molecular structure of DPNB had hydroxyl and ether groups, which promoted interactions with water, thereby contributing to its excellent froth stability. DPNB is environment friendly owing to its low volatility and, thus, a promising frother for the green and highly efficient flotation of KCl/NaCl.     

Removal of motor oil by continuous multistage froth flotation: Effect of operational parameters

A continuous multistage froth flotation column was employed to remove motor oil from water at a low concentration (500 mg/L) using an extended surfactant – branched alcohol propoxylate sulphate sodium salt (C_14-15–8PO–SO₄–Na) – as a frother. The highest separation efficiency (97% motor oil removal with the enrichment ratio of 16 for motor oil) was obtained at a foam height of 60 cm, an air flow rate of 40 L/min, a feed flow rate of 60 mL/min, a surfactant concentration of 0.3% (w/v), and an NaCl concentration of 1.5% (w/v). The process performance increased with increasing tray number but beyond 4 trays, the system could only offer lower concentrations of motor oil and surfactant in the effluent.     

Effect of frothers on removal of unburned carbon from coal-fired power plant fly ash by froth flotation

The effect of single frothers and their blends on bubble size, froth stability, and unburned carbon (UC) flotation performance was studied. Methyl isobutyl carbinol that produces smaller bubbles is efficient in floating ultrafine particles and producing concentrate. DF-250 that gives higher froth stability is effective for recovering coarse particles and improving recovery. The presence of DF-250 in the blend increases bubble size and significantly enhances froth stability, and hence the optimal flotation performance is achieved with 75% DF-250. It indicates that the frother giving high froth stability is better in UC flotation due to the little effect of UC on froth stability.     

Beneficiation of Cassiterite Fines from a Tin Tailing Slime by Froth Flotation

The beneficiation of cassiterite fines from a tailing slime in the Datun concentration plant was studied through a froth flotation process, with the chemical scheme of benzohydroxamic acid as collector, lead nitrate as activator, and pine oil as frother. It was found that tin values are mainly contained in the fine fraction of the sample and cassiterite is mostly associated with iron minerals and calcium minerals, so that the desliming treatment and the addition of dispersants and depressants can not be used as it generally results in the undesired loss of tin values. A novel flotation process with no dispersant and depressant as well as no desliming was developed. It showed that this process was effective in recovering the tin values from the tailing slime assaying 0.18% Sn, and produced a concentrate assaying 3.5% Sn with the recovery of 74.16%. It has been found that pine oil played a significant role in improving the recovery for tin values.     

Optimization of some parameters in column flotation and a comparison of conventional cell and column cell in terms of flotation performance

In this study, a comparative evaluation was made between column and mechanical flotation cells for fine coal cleaning. In addition, the optimum values of operating parameters were examined, which are important to achieve a desired separation performance in column flotation, such as the frother concentration, the collector dosage, the froth thickness, the wash water rate, the air rate and the feeding rate. The coal sample was collected from a classifying cyclone overflow stream consisting of nominally −130 μm material. Ash, volatile mater, fixed carbon and total sulfur contents of the sample were found to be 47.50%, 20.80%, 31.70% and 0.75%, respectively. Comparison of the column and mechanical flotation results indicated that column flotation was considerably more efficient than mechanical flotation for fine coal cleaning. High froth thickness and wash water addition during column flotation made it possible to obtain cleaner coals. The column flotation produced a 15.60% product ash with a 50.92% clean coal yield and 81.85% combustible recovery.     

A flotation study of refuse pond coal slurry

The flotation behavior of a refuse pond fine coal slurry sample was studied using mechanical and column flotation techniques. Flotation parameters investigated included type and dosage of frother and collector, agitation speed, scrubbing time, slurry pH, etc. for the mechanical flotation cell, and air flow rate, feed flow rate, and wash water flow rate for the column flotation. Flotation kinetics was also studied in the mechanical flotation cell. The results showed that the coal sample was very difficult to clean by flotation. Low yield (5–15%) and low combustible recovery (6–23%) and high product ash (about 22%) were obtained when methyl-isobutyl-carbinol (MIBC) was used as frother and #2 fuel oil as collector. Adjustment of operating parameters such as agitation intensity showed limited effects. However, flotation yield was significantly improved when MIBC and #2 fuel oil were replaced with frother P948 and collector SPP. Mechanical scrubbing was unable to restore the floatability of the coal sample. ‘Ken-Flote’ column flotation was inferior to mechanical flotation for oxidized coal and possible reasons were given.     

浮选药剂对嗜酸氧化亚铁硫杆菌活性的影响

引言 传统的矿山资源开发模式,要求采出高品位、易选矿,从而造成资源利用率低、能源消耗大、产生大量废矿和尾矿、环境污染严重,难以适用于品位较低的矿物资源.     

Using Alternative Chemicals in the Flotation of Heavy Metals from Lead Mill Tailings

Abstract

The U.S. Bureau of Mines (USBM) investigated alternative chemicals for the flotation of heavy metal values from southeast Missouri lead mill tailings. The objectives of the study were to lower the Pb remaining in the reprocessed tailings to <500 ppm, concentrate the metal values, and lower the overall toxicity of the flotation reagent scheme. Due to the high toxicity of classic flotation chemicals, collectorless flotation, as well as nontoxic or less-toxic chemicals, was studied for use in the flotation process. The investigation centered on the National tailings pile in Flat River, MO. Advantages to using alternative chemicals for the flotation process are presented. Novel reagent schemes are discussed for the treatment of the tailings. Various nontoxic or less-toxic oils were tested, and a substitute for sodium sulfide was investigated. Using a food additive oil, soda ash, and a frother as the reagent scheme, froth flotation recovered 89% of the Pb values. Further scavenging lowered the Pb remaining in the reprocessed tailings to <500 ppm. A less-toxic substitute for sodium cyanide was also studied for use in the cleaner flotation stages. Preliminary results indicate that the food additive oil, canola oil, to be as effective as classic sulfide flotation reagents.     

Modeling the Relationship between Froth Bubble Size and Flotation Performance Using Image Analysis and Neural Networks

Machine vision technology now offers a viable means of monitoring and control of froth flotation systems. In this study the relationship between process conditions and the surface bubble size as well as the process performance in the batch flotation of a copper sulfide ore is discussed and modeled by neural networks. Flotation experiments are conducted at a wide range of process conditions (i.e., gas flow rate, slurry solids %, frother/collector dosage, and pH) and the froth mean bubble size along with the metallurgical parameters are determined for each run. An adaptive marker based watershed algorithm is successfully developed for segmentation of the froth images and measurement of the bubble size at different conditions. The results show that there is a strong correlation between process conditions and the froth mean bubble size, which is of great importance for control purposes. Even though the metallurgical parameters can be estimated from the froth mean bubble size alone, other froth features (i.e., froth velocity, color, and stability) are required to be measured in order to achieve more accurate predictions of the process performance.     

Coal flotation using a biosurfactant from <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> as a frother

A biosurfactant-producing bacterial species (Pseudomonas aeruginosa) was grown in a mineral solution with gas oil as the source of carbon and energy. The biosurfactant was recovered from the solution by collecting the foam on the surface and drying. It had critical micelle concentration of 100 ppm. Froth characterization showed that the biosurfactant was superior to methyl isobutyl carbinol (MIBC) in terms of froth height and stability. The biosurfactant was examined in coal flotation as a frother. The combustible matter recovery of 72–79% with 10–15.5% ash content supporting 55–57.5% separation efficiency seemed promising enough to introduce the biosurfactant from Pseudomonas aeruginosa as a new frother.     

Oil recovery from oil in water emulsions using a flotation column

A flotation column was used to recover oil from oil in water emulsions. The feed oil concentrations investigated were relatively high, in the range of 0.25 to 8 percent by volume. Previous studies using conventional flotation cells dealt with very dilute systems where the oil concentration was less than 0.1 percent by volume. The oil recovery was found to decrease with an increase in the feed oil concentration. The addition of wash water to the froth zone of the column had little effect on the oil recovery. The oil recovery decreased with increasing feed flow rate and surfactant concentration. The effect of increasing the gas flow rate was to initially increase the oil recovery. The oil recovery data were analyzed using a kinetic model. The order of the flotation kinetics was found to be 0.6. The gas hold-up behaviour of the recovery and the froth zones of the flotation column is found to correlate well with the drift-flux model.     

Comparative study of the performance of conventional and column flotation when treating coking coal fines

Investigations were carried out on coking coal fines by conventional cell and column flotation techniques. The effects of different operating parameters were evaluated for both conventional and column flotation. The coal fines were collected from Bhojudih washery, India. These coal fines averaged 24.4% ash, 19.8% volatile matter and 53.8% fixed carbon on a dry basis. A commercial grade sodium silicate, light diesel oil and pine oil were used as depressant, collector and frother respectively. The flotation performance was compared with release analysis. The conventional flotation results indicated that a clean coal with 14.4% ash could be obtained at 78.0% yield with 88.4% combustible recovery. The ash of the clean coal could be further reduced to 10.1% at 72.0% yield with 85.6% combustible recovery by using column flotation. The column flotation results were close to those obtained by release analysis.     

泉店选煤厂浮选系统改造

通过分析泉店选煤厂原浮选系统工艺流程,提出了选煤厂主要存在浮选尾煤灰分低,浮选药耗高,浮选系统处理能力偏低,浮选床效率低,浮选精矿池泡沫量大等问题。针对选煤厂存在的问题,提出2种改造方案,并最终确定采用新建浮选车间并安装2台浮选机替换原有浮选床的改造方案。改造完成后,泉店选煤厂浮选尾煤灰分、精煤产率和可燃体回收率分别提高了55.61%,43.86%和44.51%,精煤灰分降低了0.29%,药剂用量减少了0.22 kg/t;浮选精矿池泡沫量明显降低,加压过滤机上料情况明显好转,处理量增大,且减少了1台空压机的使用;选煤厂每年增加精煤收益,节省电费和药剂费用总计12770.74万元。     

云南某中低品位胶磷矿浮选试验研究

对云南某中低品位胶磷矿进行了浮选试验研究,探索了磨矿细度、硫酸用量、磷酸用量、捕收剂(YP6-2B)用量对浮选指标的影响,结果表明:采用1粗1精开路单反浮选工艺流程,在磨矿细度为-0.074 mm质量分数占90.56％、H2SO4用量为15.0 kg/t、H3PO4用量为3.5 kg/t、YP6-2B用量为1.5 kg...     

On Fiber Rejection Loss in Flotation Deinking

Reducing fiber rejection loss in flotation deinking is very important to conserve natural resources and reduce the cost of secondary fibers in paper recycling. This study examined two aspects of the problem, fiber consistency in the rejection stream and rate of froth (or wet stream) rejection. Flotation experiments were conducted using both nylon and wood fibers in column and commercial bench‐scale flotation deinking cells. It was found that increased froth stability resulted in a lower fiber consistency in the wet reject stream. However, it also increased rejection rate of the wet stream. As a result, the total fiber rejection loss was increased with the increase of froth stability. The results obtained suggest that controlling froth stability through reducing frother application and froth rejection are effective ways to reduce fiber yield loss in flotation deinking. This study also experimentally measured water and fiber drainage in fiber suspended froth to explain the effect of froth stability on fiber consistency in the reject stream using froth drainage dynamics.