Water-only laboratory coal fractionation using the reflux classifier

Due to health and environmental factors involved with standard float-sink analytical methods, a water-only fractionation procedure was investigated. A laboratory scale 105 × 105 mm reflux classifier was built and used to fractionate fine coal into a number of density classes. The procedure was tested against standard float and sink methods. The reflux classifier was found to be an effective fractionation method, especially if the fractioned samples were to be used in further chemical or reactivity investigations that could be affected by the dense medium adhering to the coal particle surfaces. The procedure was easier, safer and less tedious to perform in the laboratory. Higher density cuts could be achieved, and any number of density intervals could be prepared. It was also confirmed that the separation in the reflux classifier was not totally independent of particle size but it operated well for narrow size distributions above 355 μm. Tracer tests were also done, and it was shown that tracer partition results were a poor predictor of the reflux classifier performance because of hindered settling effects.     

浮选尾煤再选试验研究

以钱家营选煤厂浮选尾煤为对象,进行再选试验研究。对煤样进行粒度分析,发现高灰细泥含量很高,决定采用反浮选预先脱泥,并探索了药剂用量对反浮选效果的影响;脱泥后的产品进行磨矿再选,工艺流程为:"反浮选─磨矿─再选"流程,最终得到了灰分为13.96%,产率为25.96%的精煤,采用该流程处理浮选尾煤可提高选煤厂经济效益。     

动力煤选煤厂煤泥浮选降灰提质增效试验研究

高剪切调浆作为煤泥浮选预处理技术,对浮选过程强化具有积极作用。本次研究以内蒙古自治区鄂尔多斯市乌审旗图克镇葫芦素煤矿的煤样进行一系列的调浆浮选实验,研究了高剪切调浆预处理对于该煤样浮选的影响。结果表明：FDJ+Q1药剂组合下,高剪切调浆浮选比常规浮选可燃体回收率提高了3.79个百分点;在可燃体回收率相近的情况下,可节省捕收剂用量37.5%;浮选动力学实验结果表明,经过高剪切调浆预处理,前两个20 s内可燃体回收率分别提升了20.02%和25.99%,90 s时基本完成分选过程,浮选速度常数增大了近50%。EKOF+仲辛醇药剂组合下,高剪切调浆强大的剪切力与涡流效应会使复合药剂中的起泡剂在调浆阶段便发挥作用,气泡携带煤粒上浮,并带走未及时分散的药剂,造成药剂的浪费,恶化浮选效果。     

Recovery of coal fines using column flotation

Tests carried out on 100mm dia × 2300mm high flotation column using coal fines from the coking coal washeries at Sudamdih, Patherdih, Kathara and Moonidih (India) have shown that the performance of the column is superior to that of the conventional cells with respect to the grade and recovery of the product. The column is found to operate efficiently both on coarse and fine fractions in the feed. The reasons for the superior performance of the flotation column have been analysed.     

Influence of coal particles on froth stability and flotation performance

Solid particles have significant effect on flotation froth. In this research, the effects of coal particles of different size and hydrophobicity on froth stability and flotation performance were studied. The froth stability was measured in both the froth formation and froth decay processes by maximum froth height, froth half-life time and water recovery. The results show that fine particles of moderate hydrophobicity contributed most to maximum froth height in the froth formation process and were most favorable for flotation. Fine hydrophilic particles stabilized the froth in the froth formation process but the froth half-life time was very short due to the high water solid ratio. High hydrophobic particles of both fine and coarse size fractions greatly increased the froth half-life time in the froth decay process. But the froths were very rigid and the maximum froth heights were very low. The presence of fine hydrophobic particles was very unfavorable for the recovery of coarse particles.     

甘肃某铷多金属矿浮选锂云母选矿试验研究

甘肃某铷多金属矿中主要矿物成分比较简单,以长石、石英、云母为主,铷主要以类质同象形式分布于钾长石、锂云母中,矿物中铌、钽主要以铁铌锰矿、钽铁铌锰矿和铌铁钽锰矿形式存在。该矿石云母嵌布粒度范围广,嵌布关系复杂,重选难以回收,本试验研究确定采用浮选回收。在对该铷多金属矿进行矿石性质研究基础上,采用磨矿-脱泥-浮选工艺流程回收矿石中的锂云母,可获得Rb2O品位0.75%,回收率为28.31%的云母精矿。该试验研究结果可作为开发利用该类铷多金属矿的锂云母回收利用的基础技术依据。     

浮选尾煤截粗系统在煤泥水系统中的应用

介绍了吕家坨选煤厂在回收浮选尾煤中的粗粒煤、降低煤泥水系统的处理压力和提高尾煤的经济效益等方面的经验,并阐述了在煤泥的深度处理、煤炭产业的产品结构方案优化与实践等方面的探索。     

云南某铜选厂尾矿再选试验

云南某铜选厂矿石矿泥含量大,导致尾矿铜品位高并还含有大量矿泥。尾矿中铜主要分布在+37 μm粒级,铜在该粒级分布率为66.07%;-10 μm粒级产率为44.39%,而铜在该粒级分布率仅11.41%。采用旋流器预先脱泥、脱碳工艺进行预处理,在旋流器锥角为10°、沉砂口直径为3 mm、给矿压力为0.15 MPa、给矿浓度为11%时,获得的沉砂铜品位为2.35%、回收率为72.41%。沉砂中铜虽然主要以次生硫化铜形式存在,但铜的氧化率达30%以上。为确定沉砂的合理选矿工艺,进行了硫化铜、氧化铜依次选别和硫化铜、氧化铜混合选别探索性对比。结果表明,硫化铜、氧化铜依次选别工艺指标优于硫化铜、氧化铜混合选别工艺。采用硫化铜、氧化铜依次选别工艺,在磨矿细度为-0.074 mm占90%的条件下,以水玻璃、六偏磷酸钠为脉石抑制剂、硫化钠为氧化铜矿物活化剂、丁基黄药为捕收剂进行闭路浮选,获得了精矿铜品位为15.16%、作业回收率为81.05%、对原矿回收率为58.69%的选别指标。     

双龙镍蛇纹石矿脱泥浮选试验研究

针对双龙镍蛇纹石矿进行Ni浮选综合回收试验研究,蛇纹石矿磨矿易泥化,影响Ni浮选指标,通过试验对比表明浮选前需脱泥。探讨摇床脱泥工艺条件,确定了摇床粗选-粗选中矿再选-摇床混合精矿浮选工艺流程。然后通过磨矿细度、浮选药剂制度调整,最终获得了精矿Ni品位8.20%,Ni回收率14.09%的综合利用优良指标。     

低阶煤泥浮选的研究

用现代浮选理论对低阶煤难浮问题进行了探讨，通过对次烟煤和风化煤表面性质的分析，提出改善低阶煤的浮选效果的措施，这些措施主要包括低阶煤的表面改性和浮选机性能的改进。实验室试验和工业应用的结果表明，这些措施大大地改善了低阶煤的浮选效果，浮精产率提高16％～33％，浮精灰分降低0．3％～0．7％；对于风化煤泥浮选，其浮选完善指标达51％。     

The flotation separation of scheelite from calcite using a quaternary ammonium salt as collector

The flotability of scheelite and calcite was studied with Dioctyl dimethyl ammonium bromide (BDDA). The experiments were conducted on individual and mixed minerals as a function of pH with a micro-flotation cell. And oleic acid was tested for comparison. The flotation results revealed that the performance of BDDA is better than that of oleic acid and the best separation could be achieved with BDDA over the pH range 8-10. Through preliminary analysis, it is concluded that BDDA reacts with scheelite through electrostatic interaction.     

Reverse flotation of coal—A novel way for the beneficiation of coal fines

South African coals have a much higher ash content than European coals. Consequently, ash entrainment is often a problem in the flotation of South African coal, since it adversely affects the concentrate grade. It has thus been very difficult to produce a low ash metallurgical export coal by this process. This paper presents a novel method aimed at reducing entrainment, viz. reverse flotation. The method involves the simultaneous flotation of the ash and the depression of the coal using cationic amine surfactants. Initial flotation testwork on liberated coal/ash mixtures has shown the excellent ash collecting ability of quaternary amines. For example, a concentrate ash recovery of 92% was achieved from a feed “coal” with an ash content of 54%. The tailings (ie product) ash was 12%. Coal depression was less successful; in the same experiment coal recovery into the concentrates was 27%. Improving the coal depression by altering the pH is being investigated.     

Effects of oils and lubricants on the flotation of copper sulphide minerals

The effects of the addition of oils and lubricants commonly encountered in mining and processing copper sulphide ores on the subsequent flotation of copper minerals was investigated by laboratory scale testing. The project arose as a result of intermittent uncontrollable frothing and a drop in selectivity observed at an Australian copper-gold concentrator. The addition of distillate to the grinding stage actually increased selectivity in the subsequent copper mineral flotation but other oils and lubricants used at the plant had detrimental effects on selectivity and frothing behaviour. A degreaser used in maintenance operations dramatically lowered copper grade and generated a very stable and sticky froth even at low concentrations. Similar detrimental effects on gold metallurgy were also observed. Mineralogical examination of flotation products verified that the decrease in grade of the concentrates was due to the flotation of free gangue minerals and not due to any liberation problems. Possible mechanisms for these effects aer discussed. Anecdotal evidence for these effects abound in discussions held with plant metallurgists, but little published data on these effects have been located.     

The effect of the reagent suite on froth stability in laboratory scale batch flotation tests

In batch flotation tests conducted on ores from the Merensky reef, changes in froth stability invariably occur with variations in the reagent suite. The main reagents are collectors (primary and secondary), activators, depressants and frothers. Since the particles entering and leaving the froth in a batch flotation system are continuously changing, the stability of the froth can vary. Under these conditions the simplest measure of froth stability is the measure of water recovery at a fixed froth height. The batch flotation system developed at UCT allows for the separation of gangue which is entrained relative to gangue which is floated. It has been found that the presence of naturally floatable gangue (NFG) leads to froth stabilisation, whereas the presence of hydrophobic sulfide minerals may lead to destabilisation of the froth depending on the hydrophobicity (contact angle) of the sulfide minerals. This can vary with ore type since particle shape and amount of particles present can influence the extent of destabilisation. At low depressant dosages sodium isobutyl xanthate (SIBX) always results in lower froth stability than sodium ethyl xanthate (SEX). The frothing nature of dithiophosphate leads to increased froth stability and the addition of copper sulfate results in destabilised froths. Increasing depressant dosage reduces the stabilising influence of NFG and the depressant type (guar gum or CMC) also affects froth stability. Frother can be used in an attempt to overcome the destabilising effects of high depressant dosage. This work examines the effect of variations in the reagent suite and uses water recovered at a fixed froth height as an indication of froth stability in order to analyse these effects on the recovery of sulfide minerals, floatable gangue and entrained gangue.     

The dependency of the critical contact angle for flotation on particle size - Modelling the limits of fine particle flotation

The flotation behaviour of fine particles is studied in this work. Fine methylated quartz particles within the size range from 0.2 to 50 μm, and with varying contact angles, were floated in a mechanical flotation cell. Results indicate that particles of a given size need to possess a minimum critical contact angle, which increases in value as particle size decreases, for flotation to be initiated. As a consequence, a non-floating component exists within a given size fraction. This is interpreted as a fraction consisting of particles below the critical contact angle for flotation for that size. The critical contact angle for flotation is explained in terms of the existence of an energy barrier for bubble-particle attachment. The flotation results are interpreted by means of [Scheludko et al., 1976] and [Drelich and Miller, 1992] models for the floatability of fine particles. The experimental data compared very well with calculations using the Drelich and Miller equation, allowing extension to the prediction of the critical contact angle for flotation down to particle sizes well below the previous limits investigated, bridging the gap existing in the literature.     

气肥煤浮选降灰试验研究

为考察山东济北矿区气肥煤煤泥降灰的可行性,分别以柴油和仲辛醇(分析纯)为浮选药剂,采用拓展化浮选试验的方法,重新设计浮选流程,对煤泥进行了粗选试验和一次精选试验.试验结果表明:最佳浮选药剂用量为1.0 kg/t、药剂比为5:1,矿浆浓度为80 g/L、搅拌速度为1 800 r/min,精选多次刮泡条件下,时间累计在15...     

Effect of slurry rheology on gas dispersion in a pilot-scale mechanical flotation cell

This paper investigates the effect of slurry rheology on gas dispersion in a 100 l pilot-scale Batequip mechanical flotation cell. The study is conducted using Kaolin, Bindura nickel and Platreef slurries. All three ores display typical non-Newtonian rheological behaviour. The slurry yield stress and viscosity increase exponentially with solids concentration. Bubble size and gas hold-up vary from 0.60 to 1.10 mm and 2% to 15%, respectively. At low/moderate solids concentrations, bubble size and gas holdup display characteristic trends, as noted in numerous literature studies. At high solids concentrations, both bubble size and gas holdup decrease significantly, which is an unexpected finding. This is attributed to the formation of a ‘cavern’ of slurry around the impeller, due to the very high slurry yield stresses. This ‘cavern’ results in the generation of small bubbles in the impeller zone, but poor dispersion of these bubbles throughout the cell, resulting in low gas hold-ups.     

低灰浮选尾煤的磨矿脱泥浮选工艺试验研究

针对河北唐山地区煤炭黏土含量大、多高灰细泥、浮选效率低的问题,采用磨矿、小锥角水力旋流器脱泥、分步释放浮选等试验方法进行了浮选工艺试验研究。结果表明：采用150 mm与75 mm旋流器串联脱泥工艺,底流和溢流灰分差值为13.05%,说明旋流器串联脱泥工艺起到了较好的效果,能分离部分高灰细粒级煤泥,对底流进行分步释放浮选试验研究,在保证精煤质量前提下,精煤产率也相应得到提高,说明采用小锥角水力旋流器对原煤泥进行浮选前脱泥,能够有效降低高灰细粒级对浮选的影响,提高精煤的浮选效率;浮选尾煤灰分仍然较低,为38.27%,对低灰尾煤进行磨矿-脱泥-浮选试验,精煤产率为35.47%,综合精煤产率（占全级）相比较原煤泥直接浮选提高率达54.20%。     

正反浮选分支精选工艺在大峪口胶磷矿的工业化应用实践

大峪口胶磷矿浮选工艺为正反浮选工艺流程,正浮选工艺采用脂肪类捕收剂进行加温浮选,该工艺存在中间产品,作业产率高、粗选泡沫体积大、后续作业浮选机输送载矿泡沫能力不足、精矿泡沫外溢、浮选作业指标波动较大等问题,导致系统实际生产能力只达到设计能力的80％.针对该问题,提出了正反浮选分支精选工艺流程,并对原生产工艺和设备布置进...