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选煤厂的操作,传统上一直不重视质量控制而只注重于达到高的回收率。最近对于世界能源的研究表明,煤精选工业趋向于采取更加先进的方法。需要量的增加以及对环境影响关注,要求采用生产能力高的有效率的煤精选工艺,以满足工业生产的要求。采用细粒级煤浮选精选工艺是改善工厂生产的一种方法。可是目前的工厂生产实践表明得到的品位和回收率都在很大的范围内波动。这是由于浮选给矿量与固定的操作变量(例如试剂加入速率或浮选槽的液面水平)波动的结果。最佳浮选操作的一种方法是研制一些检测器,该检测器能够检测重要过程的变量随时间的变化。一旦这样一些检测器研制出来,就能测定出过程对控制变量的反应。这些关系将揭示过程的品位一回收率特征曲线、浮选给矿条件以及主要的可控变量之间的相互作用。这些关系同时能够用于过程的模拟和控制。在控制煤浮选有效方法研究中所要求的一个关键性的检测器,是一种能够测定煤浆中灰分含量的器件。一种为实现这一功能而研制的检测器,由一个配有Gd—153放射源的浓度计以及一个装有Gd—109放射源并能测量反向散射低能光子强度的灰分检测器组成。试验工作最初是在实验室规模下进行的,目的是验证这种检测器所依据的基础理论。尔后,在宾夕法尼亚的一个煤选厂的浮选流程中,对该检测器件进行了在线扩大试验。到目前为止试验工作着重于测量浮选给矿、精矿以尾矿中的灰分含量。本文将介绍测验程序及试验结果分析的详细情况。业已研制出的这种检测器是通用的,并能用来对矿浆中多种矿物进行在线测量。然而,目前的试验仅严格地限于煤矿浆中灰分的在线测定。
The operation of a coal preparation plant has traditionally failed to focus on quality control and only focused on achieving high recovery rates. Recent research on world energy shows that the coal concentrates industry tends to take a more advanced approach. Increasing demands and environmental concerns have led to the adoption of an efficient coal-based process with high productivity to meet the requirements of industrial production. The use of fine-grained coal flotation process is a way to improve the factory production. However, current plant practices have shown that the grades and recoveries obtained fluctuate widely. This is the result of fluctuations in flotation volume and fixed operating variables such as reagent addition rate or liquid level in the flotation cell. One way to optimize the flotation operation is to develop detectors that can detect changes in variables of important processes over time. Once such detectors have been developed, the reaction of the process to the control variables can be determined. These relationships will reveal the grade-recovery curve of the process, the interaction between the flotation feed and the major controllable variables. These relationships can be used both for process simulation and control. A key detector required in the study of effective methods of controlling coal flotation is a device capable of measuring ash content in coal slurry. One detector developed for this purpose consists of a densitometer with a Gd-153 source and an ash detector equipped with a Gd-109 source and capable of measuring the backscattered low-energy photon intensity. The experimental work was originally carried out on a laboratory scale in order to verify the basic theory upon which such a detector was based. Later, at a flotation process at a coal processing plant in Pennsylvania, an on-line expansion of the test device was conducted. So far, the experimental work has focused on the measurement of the flotation to the ore, the concentrate to tailings ash content. This article will introduce the details of the test procedure and the analysis of the test results. The detector, which has been developed, is versatile and can be used to make on-line measurements of many minerals in the slurry. However, the current test is strictly limited to the on-line determination of ash in coal slurry.