A demand side management study model for an on–off heap leach pad

Abstract

In today’s world it is imperative to understand that the power demand of industrial and mining operations should be as economical as possible. This is especially necessary with the inevitable depletion of our natural recourses such as coal, oil and gas which is used in the production of electricity. Since no replacement is currently available for carbon based electricity in Southern Africa, there is significant pressure applied by utility suppliers to force consumers to use energy wisely. The challenge is to run plants as efficiently as possible by decreasing operation’s electrical footprint. High electrical costs and tariffs are the next primary driver for plant owners to use electricity efficiently. Whether applying for allocation of power to a local electricity supplier, designing for optimisation of capital and operation expenditures, managing operation peak demands or for all of the above, a consumer must have a method of evaluating the plant’s demand side demand. Demand side consumption is the energy consumed by the consumer at the tie–in point to the supplier and is represented by a load shape. A study on how to reduce the demand of electrical energy consumed by the consumer at this interface is called a demand side management study or DSM study. A DSM study is part of a DSM process. On existing plants where stakeholders would like to know their demand side consumption or load shape in order to implement a DSM process, measurements can be taken at the tie–in point (or also referred to as the point of interest). The question arises, what about clients that would like to conduct a DSM study (or the entire DMS process) on a greenfield project perhaps during the feasibility phase or basic engineering phase? In both cases very little information is available. This dissertation presents a model as part of the DSM study on a uranium plant’s leaching section for the client to use in his DSM process. The specific leaching technology to which this model is applied is called an on–off heap leach pad (OOHLP). The process followed to obtain the load shape was firstly to conduct a search for other similar studies and operations in order to find useful information and techniques. The next step was to investigate and design a prototype plant based on the client’s requirements as a case study project, namely Trekkopje Maxi located in Namibia. The equipment, components and their operational profiles were identified and from this a mathematical formula was developed and a visual model was outlined. Finally the results were verified at selected points against the same calculated by an electrical software package’s load flow simulation tool. The OOHLP’s model developed in this dissertation can be used in future studies to optimize the electrical design of leach pads.