Automatic control of a laboratory flotation column

The operation of industrial flotation columns requires the control of at least two variables, the interface position and the bias rate, by manipulation of some appropriate operating variables. Problems arise due to the reliability of existing methods of measuring the bias (i.e bias = tailings water - feed water), a situation which has often forced the industry to disregard this control loop. Moreover, when using such a measuring approach, the identification of the process dynamics is impossible. A second problem arises from the possible interaction between both control loops that might call for the use of a more complex multivariable control strategy.Recent work done at Laval University has demonstrated the feasibility of an independent sensor for bias, which models the relation between the conductivity profile across the interface and the bias value using a neural network algorithm. A 250 cm height, 5.25 cm diameter Plexiglas laboratory column was equipped with a series of conductivity electrodes in its uppermost part (across the interface) to measure both interface position and bias rate. Using such equipment, the flotation column dynamics was identified. The results thus obtained permitted the design and implementation of a distributed PI control strategy, where bias was associated to wash water rate and froth depth to tails rate. Both PI controllers were tuned using a frequency-response tuning method. Results of both identification and process control are presented and discussed.     

Dynamic model of a flotation column

A linear multivariable model for a flotation column is derived from process analysis and experimental data. The data have been taken from a pilot-scale column (height 720 cm; diameter 5.1 cm) with all necessary instrumentation installed. The flotation column was operated in a water-air system. The model has been derived aimed at utilisation in the design of the control system. The model describes the relationship between controlled variables (froth layer height, bias and air holdup in the recovery zone) and manipulated variables (wash water, air and non-floated fraction flowrates). It has been validated comparing the experimental data with those obtained from simulations. Finally, the conditions under which the model is applicable are presented.     

Selective detachment process in column flotation froth

The selectivity in flotation columns involving the separation of particles of varying degrees of floatability is based on differential flotation rates in the collection zone, reflux action between the froth and collection zones, and differential detachment rates in the froth zone. Using well-known theoretical models describing the separation process and experimental data, froth zone and overall flotation recovery values were quantified for particles in an anthracite coal that have a wide range of floatability potential. For highly floatable particles, froth recovery had a very minimal impact on overall recovery while the recovery of weakly floatable material was decreased substantially by reductions in froth recovery values. In addition, under carrying-capacity limiting conditions, selectivity was enhanced by the preferential detachment of the weakly floatable material. Based on this concept, highly floatable material was added directly into the froth zone when treating the anthracite coal. The enriched froth phase reduced the product ash content of the anthracite product by five absolute percentage points while maintaining a constant recovery value.     

旋流微泡浮选柱和机械搅拌式浮选机工艺效果对比

简要介绍了邢台矿选煤厂煤泥处理工艺流程,详细分析了浮选柱与浮选机各自的分选原理和特点,并根据邢台矿选煤厂工艺流程和入浮煤泥性质,通过对选前脱泥与不脱泥重介条件下旋流微泡浮选柱和机械搅拌式浮选机浮选工艺效果的分析,对比了两种浮选设备的分选工艺效果。     

Mathematical models of the column flotation process a review

Mathematical modelling is a valuable quantitative instrument, which is being effectively employed to the column flotation process in order to predict its metallurgical performance. This paper presents an up-to-date assessment of the various mathematical models for column flotation currently available under the categories of kinetic models and non-kinetic models and also identifies a number of associated shortcomings.     

Evaluation of models for air recovery in a laboratory flotation column

One of the more interesting recent topics in flotation modelling is the association between the fraction of air that overflows to the concentrate as unbroken bubbles (air recovery, α) and concentrate recovery. This paper analyses several models to estimate air recovery. These models were tested using experimental data obtained with a laboratory flotation column (2 m high; 0.095 m diam.), which was used to float sphalerite. Predictions from these models were compared with the results obtained by image analysis. The aim of this last technique was to have a reference measurement, quantifying by visual detection (manual method) the bubbles bursting on the surface. Based on the experimental results, the best models were identified. This kind of comparison is valuable for simulator developers.     

炼焦中煤柱浮选试验研究

以山西新裕选煤厂重介中煤为研究对象,通过破碎、细磨释放中煤有机组分,利用旋流和无旋流两种进气结构的浮选柱进行了浮选对比试验,研究结果表明:旋流进气结构的浮选柱在大充气量时,中煤可燃体回收率可达66.67%;无旋流进气结构的浮选柱在较小的充气量时,中煤浮选产品灰分可降至10.31%。在此基础上,针对中煤特点提出了"重选+粗选+精选"的中煤再选工艺。     

浮选柱代替浮选机精选在大红山铜矿的试验研究

针对浮选柱结构简单、投资省、能耗低、浮选精矿富集比高的特性,大红山铜矿开展CPT浮选柱代替三次浮选机精选作业的生产工业试验研究,探索浮选柱替代三次浮选机精选后大红山铜矿的铜选矿回收率及精矿品位是否与小型分流试验一致,精矿品位及回收率均得到提高。分为两个阶段进行,分别采用浮选柱和浮选机在粗精矿再磨和不磨的两种情况下进行铜精选作业,对比分析浮选柱与浮选机的精选效果。两个阶段的工业试验结果表明铜浮选精矿品位基本一致,而CPT浮选柱精选较浮选机三次精选的回收率下降了0.79个百分点的指标。从原矿性质及铜矿物浮选条件分析得到,大红山铜矿的岩石性质主要为铜铁伴生矿体,铜矿物主要为黄铜矿,易浮选,浮选药剂简单,而浮选柱对+53μm粗粒级矿物的回收不充分,作业率较低,不适宜大红山矿石的铜精选作业。试验结果可为相同矿石性质的矿山提供参考。     

Froth zone characterization of an industrial flotation column in rougher circuit

In this investigation the froth zone of an industrial column (4 m “diameter” × 12 m “height”) in rougher circuit was characterized. Experiments were carried out at Miduk copper concentrator, Iran. Miduk is a unique copper processing plant which utilizes columns in rougher circuit. Cleaning and selectivity actions in the rougher froth were illustrated using solids and grade profiles along with RTD data. The impact of froth depth (FD) on overall rate constant (k) and k–S_b relationship was evaluated. Dependency of overall flotation kinetics on froth depth and gas velocity (J_g) was modeled by k = 4.97(FD)^?0.87(J_g)^0.80. Froth recovery (R_f) was estimated and modeled in terms of froth residence time of slurry (FRT_Slurry) as R_f = R_f,maxexp(?k × FRT_Slurry). Finally, the correlation between k, S_b (indicative of the collection zone performance) and FRT_Slurry (indicative of the froth zone performance) was modeled by k = 0.02 (FRT_Slurry)^?0.62(S_b)^0.82.     

Cyclonic-static micro-bubble flotation column

A cyclonic-static micro-bubble flotation column (FCSMC) was developed for mineral separation, particularly for whole flotation circuits. The FCSMC featured multiple mineralisation steps, including countercurrent mineralisation, cyclone mineralisation and pipe flow mineralisation in a single column, through which the mineralisation energy, mineralisation rate and dynamic turbulence intensity gradually increased to compensate for the decrease in the floatability of mineral particles. It thus led to highly efficient mineralisation as well as a sufficient retention time fine mineral recovery. The usability and performance of the FCSMC was assessed and further confirmed by lab-, pilot- and industrial-scale units based on magnetite ore. The iron concentrate grade reached 69% with a recovery of 95%.     

CPT浮选柱精选小型分流工业试验研究

针对浮选柱对微细粒矿物浮选和提高精矿品位方面的优越性,结合大红山铜矿浮选工艺流程的简单灵活性,在大红山铜矿二选厂采用从生产流程中分流出一部分矿浆进行CPT浮选柱试验,结合精选尾矿MLA测试结果研究浮选粗精矿再磨和不再磨两种情况下取得的技术经济指标.与浮选机相比,获得粗精矿柱浮选不再磨流程精矿铜品位提高了 1.00个百分...     

利用浮选柱进行白钨精选的探索性试验研究

利用小型浮选柱进行白钨精选的探索试验,在粗精矿品位1.2%左右的情况下,获得了精矿品位41.25%、回收率81.24%的指标,与精选采用BF型浮选机的选厂相比,精矿品位提高近10%。     

浮选机－浮选柱联合分选某硫铁矿尾矿试验研究

以广东云浮某硫铁矿选矿厂的浮选尾矿为样品,采用浮选机-浮选柱联合分选工艺进行分选,充分利用浮选机和浮选柱两种设备的特性,在保证粗颗粒回收的同时强化了微细颗粒的回收。对原矿样品的粒度和硫含量进行了分析,结果表明硫主要分布于+74 μm和-10 μm两个粒级中。通过浮选机两次粗选、两次扫选、粗精矿再磨后两次精选流程的闭路试验,可从含硫6.91%的浮选入料中获得品位为33.42%、回收率为63.82%的硫精矿。在相同的药剂用量下,通过浮选机-浮选柱联合分选,可获得品位为32.68%、回收率为70.84%的硫精矿。粒级回收率分析表明,与单一浮选机工艺相比,浮选机-浮选柱联合分选后,-54 μm细粒级的回收率明显提高,尤其是-20 μm粒级,回收率提高了将近10个百分点。     

Arsenopyrite enrichment by column flotation

Arsenic-rich, gold-bearing pyrite concentrates may be further enriched in arsenic to assist subsequent Au beneficiation. Among several amines tested in refloating a local Chalkidiki pyrite concentrate, 2-coco 2-methyl ammonium chloride proved successful by raising the grade from 9% to 22%, although total solids recovery was low. The use of a froth-stabilizing frother was also benefecial to the process. Optimum hydrohynamic conditions were: intermediate pulp flowrate, low wash water and gas flowrate; the latter abated the mixing/dispersion process in the collection zone.     

Selectivity in phosphate column flotation

The objective of this work was the study of the selectivity of apatite flotation in a column by means of kinetic analysis. The recovery and apatite content in the concentrate were correlated to the collector dosage, depressant dosage and air flow rate. The test results were subjected to statistical analysis aimed at identifying the experimental conditions producing the best P₂O₅ content and recovery.     

浮选柱中蜂窝管高效充填的设计与研究

以实现柱浮选段的层流分选环境,促进浮选柱中气泡与矿物的逆流碰撞矿化效果为出发点,通过充填结构的通道形式、孔径、层数及布置方式等主要参数的选择与设计,开发了边界成本最优且能完全充填的正六边形蜂窝管填料对浮选柱的柱浮选段进行充填。CFD流体力学数值模拟结果表明,蜂窝管充填与原先浮选柱中采用的筛板充填相比,更能有效地对柱体中由下而上流体的切向速度和径向速度进行限制。清水条件下的气含率测试。试验结果表明,蜂窝管充填的气含率降低趋势小于筛板充填和无充填的情况。某硫化铜矿工业应用指标表明,蜂窝管充填浮选柱系统获得的精矿品位与筛板充填浮选柱系统精矿品位基本持平,它的铜金属回收率达到92.92%,比筛板充填系统高出1个多百分点,硫化铜矿分选指标得到改善。     

浮选柱在某选矿厂铜镍分离作业中的应用实践

为改善某选矿厂一期和二期生产线浮选过程能耗高、指标波动大、自动化程度低的现状,将在工业试验阶段运行良好的浮选柱应用到三期新建浮选系统中。针对浮选柱系统投产后存在的问题,进行了合理地适应性工艺改进,将铜镍分离浮选工艺优化为一次粗选、三次扫选、四次精选的柱机联合流程,使铜镍互含指标基本达标,同时降低了电能消耗,提高了浮选生产效率,为浮选柱在铜镍分离作业中的进一步推广运用奠定了基础。     

某磁赤混合铁矿的柱式阳离子反浮选试验研究

为了简化流程,降低成本,对某磁赤混合铁矿选厂的磁选精矿进行了柱式阳离子反浮选试验研究,包括浮选柱的条件试验和浮选流程试验。试验结果表明,以淀粉为抑制剂,GE-609为捕收剂,采用充填型微泡逆流接触式浮选柱,对于给矿品位为39.89%的混磁精矿,通过两次粗选、一次精选、一次扫选的柱式浮选流程,可获得铁精矿品位66.07%、回收率69.82%的良好指标,达到了简化药剂制度,降低浮选成本的目的。     

旋流-静态微泡浮选柱用于铜精选的试验研究

为提高某斑岩型铜矿的精矿品位,引入旋流-静态微泡浮选柱进行精选工艺试验研究,以浮选柱两段替代原浮选机五段精选流程,可获得品位为26.45%的铜精矿,精选作业回收率达93.66%,并有利于金、银、钼等伴生金属的富集和回收.