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A decision support tool for circular stockpile management using simulation

Loubser, Zureka (2012-12)

Thesis (MScEng)--Stellenbosch University, 2012.

Thesis

ENGLISH ABSTRACT: The aim of a blending stockpile is to minimise the natural variation in properties of a material deposit. In general the reduction in variation will result in a more efficient and cost effective downstream process. Stockpile management is an important part of the production manager’s duties, as it has a significant impact on the quality and consistency of the product delivered. Decisions in this regard are mostly driven by experience and specialised expertise, and a need has been identified to implement scientific methods in the decision-making process. A representational model-driven personal decision support system was designed which aims to assist the decision making process of a production planner/manager by providing information about the expected output grade variation from a circular stockpile. The core of the decision support tool is a model that simulates the behaviour of a continuous circular blending pile. The development of the simulation model extended work done by other authors by eliminating the assumptions of constant stacker flow and vertical reclaimer slices. A user interface was developed that makes the complex calculations behind the simulation easily accessible to planning and operational personnel. The validity of the simulation model was evaluated by using data from a case study. It was found that the coneshell model offers a reasonable representation of reality in the way that it simulates the movement of the stacker and reclaimer units around the pile, and proved able to predict peaks and troughs in the output grade to within 4% of the recorded values. Preliminary validation of the chevcon model delivered positive results, but further validation measured against recorded data would be necessary before implementation is considered. The simulation model was also used to investigate the sensitivity of blending efficiency to various input parameters. Under optimised conditions the output variance generated by the chevcon model was half of that achieved with coneshell stacking, proving that the investment in chevcon stacking infrastructure is one that every production facility seeking improvement in output grade consistency should consider. The research objectives set at the start of the study have been achieved, and results indicate that the decision support tool can be used to predict and the consistency of material grade as reclaimed from a circular blending pile.

AFRIKAANSE OPSOMMING: Die doel van ‘n mengbed is om die natuurlike variasie in eienskappe van ‘n mineraalafsetting the minimiseer. In die algemeen sal hierdie vermindering in variasie ‘n meer doeltreffende en effektiewe proses tot gevolg hê. Mengbed bestuur is ‘n belangrike deel van ‘n produksie bestuurder se pligte, aangesien dit ‘n merkbare invloed op die produk kwaliteit en eenvormigheid sal hê. Besluite in hierdie verband maak meestal staat op ervaring en gespesialiseerde kundigheid, maar ‘n behoefte om wetenskaplike metodes in hierdie besluitnemingsproses in te sluit is egter geidentifiseer. ‘n Verteenwoordigende model-gedrewe persoonlike besluitnemingssisteem is ontwerp, wat die produksie beplanner/bestuurder kan bystaan in hul besluitnemingsproses deur informasie te voorsien oor die verwagte uitgaande graad variasie vanaf ‘n sirkelbed. Die kern van die besluitnemingsinstrument is ‘n model wat die gedrag van ‘n deurlopende sirkelmengbed kan simuleer. Die ontwikkeling van die simulasie model het uitgebrei op werk wat gedoen is deur ander skrywers deur die aannames van konstante stapelaar vloei en vertikale herwinnaar snitte te elimineer. ‘n Gebruikerskoppelvlak, wat die komplekse berekeninge agter die simulasies maklik toeganklik maak vir beplannings- en bestuurspersoneel, is ook ontwikkel. Die geldigheid van die simulasie modelle is geëvalueer deur data vanaf ‘n gevallestudie te gebruik. Die puntstapel model bied ‘n redelike voorsteling van die werklikheid in die manier wat dit simuleer hoe die stapelaar en herwinnaar rondom die hoop beweeg. Die model kon ook pieke en dale in die uitgaande graad voorspel tot binne 4% van die werklike waardes. Voorlopige geldigheidstoetse op die Chevcon model het positiewe resultate gelewer, maar verdere toetse met die gebruik van werklike data sal nodig wees voor implementasie van hierdie model oorweeg kan word. Die simulasie model is ook gebruik om die sensitiwiteit van vermengings effektiwiteit tot verskeie parameters te ondersoek. Onder geoptimiseerde omstandighede sal die vlak van variasie soos gegenereer deur die Chevcon model die helfde soveel wees as vir die puntstapel model. Hierdie resultaat dien as bewys dat ‘n belegging in Chevcon stapelaar infrastruktuur iets is wat elke produksie fasiliteit met ‘n belang in verbeterde vermengings effektiwiteit behoort te oorweeg. Die navorsingsdoelwitte soos uiteengesit aan die begin van die studie is bereik, en die resultate dui daarop dat die besluitnemingsinstrument wat ontwikkel is gebruik kan word om die eenvormigheid van materiaal, soos herwin vanaf ‘n sirkelmengbed, te voorspel.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/71954
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