AnStat-330 在线采样和元素分析站

<p>If the critical streams are monitored frequently as per the recommended criteria, the operators should be able to control the plant to give overall stability and best metallurgical results at minimum cost. The less critical intermediate streams can then be monitored at a lower frequency for the fine tuning of the circuit.<br/><br/> The degree of confidence required in the assay-based control decisions must be known. Streams that are more critical for control of the plant need to be monitored more frequently. Trends in plant performance will then be shown in more detail, showing effect of control actions on grade in real-time and giving greater confidence in control decisions. For example, in a base metal concentrator, the main objective might be to minimize metal losses in primary floatation while producing a particular concentrate grade in the cleaners. In addition, test work may show that recirculating loads tend to build up in the cleaning stages which is a result of recovery of excessive gangue in the rougher concentrate. Continuous analysis of tailings grades provides a critical tool in the operation of rougher flotation. On-line analysis of concentrates provides a tool to manage grade-recovery in the cleaners and better control impurities to meet the smelter requirements. </p>

<p>The elements to be analyzed are determined by the objectives of the process control strategy and the particular metallurgical problems which are anticipated from prior metallurgical test work. The frequency of analysis required, often referred to as the assay update time, depends on the following criteria:<br/><br/> - The fluctuation in assays in a given process stream considering the residence times of the processes immediately upstream<br/> - The stability of the circuit<br/> - At a minimum, the assay update times of the analyzers for the critical streams should be less than half of the retention time of the preceding process stage<br/><br/> Therefore, in the tailings stream from a scavenger bank of cells with a retention time of 5 mins, the grade can be expected to vary considerably in 2 mins during upset conditions or reactions to process control actions so on-line analysis should be made at an interval less than this to provide the best visibility of real-time plant performance. To obtain these sorts of assay update times, one requires dedicated analyzers or a centralized analyzer with just a few streams located nearby the process sample points.</p>

<p>When selecting the right online slurry analysis system, there are several capital constraints that should be considered, including<br/><br/> - Capital investment,<br/> - Economic benefits expected<br/> - Cost of on-going maintenance<br/> - Flexibility of system modules<br/> - Incremental benefits of less essential assays.<br/><br/> The economic benefits of having an on-line slurry analysis system coupled to a control system, be it manual or fully automatic, comes from one or more of the following: increase in metal recovery, improvement in concentrate grade and control of impurities, reduction in reagent consumption, decrease in operating costs, and improvement in stability of the operation.<br/><br/> These benefits have to be weighed against the capital investment of the analysis system and the cost of on-going maintenance including mechanical repairs, sample pump servicing or replacement, sample transport system troubleshooting, electronic repairs, analyzer downtime and calibration. The flexibility of hybrid systems of dedicated analyzers for the critical streams and multi-stream analyzers for the less critical streams enables the most cost effective analysis system to be selected for each particular plant. In working out what streams are to be measured, a cost benefit analysis should be carried out to guide the decision making process.</p>