矿石特性对浓缩过程水回收影响的实证模型研究

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"该资源是一篇发表在2014年《国际矿物、冶金与材料》杂志第21卷第9期的文章，作者包括Majid Unesi, Mohammad Noaparast, Seiyd Ziaedin Shafaei和Esmaeil Jorjani。文章的目的是通过实证模型研究矿石特性对浓缩过程（即固液分离中的水回收）的影响，以提升浓缩性能和水回收效率。实验使用了柱状设备进行，并用旋流器准备实验样本。" 正文: 固液分离是矿物加工和矿业工程中的关键步骤，特别是在浓缩过程中，它直接影响着水的回收率和整体工艺效率。2014年的这篇论文深入探讨了矿石特性如何影响这一过程，为提高浓缩性能和水回收提供了理论基础。文章首先强调了对固液分离机制的深入理解对于优化浓缩过程的重要性。在矿业操作中，浓缩过程通常涉及将含有固体颗粒的悬浮液分离，以减少液体的排放并回收有价值的固体。水回收率的提高不仅意味着能有效利用水资源，还能降低环境影响和运营成本。作者通过进行一系列的柱状试验，开发了一个实证模型来研究矿石特性对浓缩过程的具体影响。这些试验中，他们使用了旋流器来制备实验所需的样本，旋流器是一种广泛用于固液分离的设备，可以有效地将不同粒度的颗粒分选出来。模型的建立和验证表明，矿石的物理性质，如粒度分布、形状、密度以及表面性质，都显著地影响着水的回收。例如，较细的颗粒可能导致更高的水吸附，从而降低水的回收率；而矿石密度的差异可能影响沉降速度，影响固液分离的效率。此外，矿石表面的润湿性也起着关键作用，亲水性矿石更倾向于形成稳定的悬浮液，增加分离难度。通过这个模型，研究人员能够预测不同矿石条件下浓缩过程的性能，为实际操作提供指导。例如，通过调整作业参数，如絮凝剂的使用、搅拌速度或添加助剂，可以改善特定矿石类型的固液分离效果，进而优化水回收。这篇论文贡献了一种实用的工具，有助于矿业工程师更好地理解和控制浓缩过程，从而提升水循环利用的效率，降低成本，同时减轻环境负担。其研究结果对于矿物加工技术的改进和环保型矿业实践具有重要意义。

M. Unesi et al., Modeling the effects of ore properties on water recovery in the thickening process 853

In order to study the effects of ore properties on the

thickening process, the researchers attempted to run various

experiments in the plant conditions for all samples. Since

the samples were taken as a suspension from the hy-

dro-cyclone, and were then treated by tailing wastewater,

the thickening behavior can only be attributed to ore proper-

ties. The samples were prepared to the required density (the

feed concentration in all experiments was 10% solid in sus-

pension) based on experimental conditions. The pH value of

the sample was 11, equal to the industrial pH value, in all

experiments. The anionic polyacrylamide with a high mo-

lecular mass (NF43U from SNF) was used to flocculate the

suspension and was prepared at 0.25 g/L — the industrial

dosage. Since the amount of flocculent consumption in the

Sarcheshmeh paste thickeners is usually between 20 and 30

g/t, the pilot tests were performed at 25 g/t.

2.2. Pilot column

A plexiglass column, which was 4 m in height and 0.2 m

in internal diameter, was used for pilot experiments. The

feed and flocculent were introduced to the column at a

height of approximately 3 m via a feed-well by peristaltic

pump. The dilution water was also introduced at this column

height. Overflow was then collected by a peripheral launder.

The interface between the feed and clarified water could be

observed. Suspensions were then transferred to a hy-

dro-cyclone equipped with overflow and underflow boxes.

Based on the experimental condition, either HO, HU, or HF

was transferred to the pilot column. Shortly after the column

was filled, three zones were distinguishable. The top of the

column was characterized by a clarified zone. In the middle

zone, individual aggregates were observed to be settling.

The lower zone was an opaque region in which the solids

settled at a slower rate. There was a marked interface be-

tween the middle and lower zones that is referred to herein

as the “bed height” or “bed depth”. It should be noted that

this interface was not necessarily the point at which the sol-

ids became networked.

In addition, discontinuous tests were conducted in the

start-up step. After column start-up, the bed of solids began

to form, and the relevant interface could be readily detected

(by eye). The bed height gradually increased as solids ac-

cumulated, and when the solid bed reached the desired

height (0.5 to 2.5 m), the time was recorded using a chro-

nometer. In continuous tests, several column experiments

were performed. The results for solid flux (solid flow rate in

feed or underflow per unit area), bed height, and ore proper-

ties (particle size and solid density) for each run are pre-

sented in Table 3. The bed height was allowed to increase to

approximately 80% of the target height, at which the under-

flow pump was turned on. This was done to compensate for

the slow dynamical response in the column. In practice, the

speed of the underflow pump needed to be periodically ad-

justed to keep the bed height constant due to the variation in

underflow solid content. Therefore, the underflow rate var-

ied with the variation in speed of the underflow pump to

control the bed height. Over the course of a run, the bed

height was maintained within 10% of the nominal height. In

the first time of each run, the average underflow rate in-

creased, which corresponded to a decrease in solid content

of the underflow as the system moved to the steady state.

Furthermore, the underflow solid content was initially un-

steady. After a while, this fluctuation died out and the un-

derflow solid content remained fairly constant.

For each run, the column was allowed to operate for suf-

ficient time to achieve the steady state prior to sampling com-

mencing. On this basis, the steady-state conditions would

take anywhere from 2 to 5 h, depending on the bed height.

After this time had elapsed, column underflow samples were

collected at 15 min intervals. No solids were recorded in the

overflow for each condition used in the experiments, and the

supernatant was always observed to be clear.

3. Results and discussion

A series of experiments were performed in pilot scales to

study and model the thickening behavior. Their results are

presented below.

3.1. Discontinuous tests

Fig. 1 presents the bed formation curves, where the col-

umn was discontinuously operated at different solid fluxes

(

). Bed formation in the HF samples tends to the HO curve

at low

(10 t⋅m

−2

⋅d

−1

) and tends to the HU curve at high

(28.5 t⋅m

−2

⋅d

−1

). The long time at a lower

creates an op-

portunity for fine particles to settle easily. Therefore, high

solid density and particle size did not play a decisive role in

bed formation, but their effects appear at higher

. In addi-

tion to solid flux, bed formation depends on compressibility

caused by smooth slope changes in some parts of the curves.

Bed compression usually occurred at the 2–2.5 m column

height. This was not observed in the HO and HU samples,

except at a higher

of 28.5 t⋅m

−2

⋅d

−1

(with the HO samples).

This effect was repeated in the HF samples, which could be

due to coarser and finer particle interactions or the interac-

tion of clay, quartz, and metallic minerals. Therefore, it is

postulated that the particle size distribution and the domi-

nant minerals in the samples cause this effect.

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矿石特性对浓缩过程水回收影响的实证模型研究

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