pH%20advanced%20process%20control%20solution%20for%20Impala%20BMR%20first%20stage%20high%20pressure%20acid-oxygen%20leach

1
pH advanced process control solution for Impala
BMR first stage high pressure acid-oxygen leach

• Abdullah Khan
• 26 February 2009
• Hydrometallurgy Conference
• Muldersdrift

2
Agenda

• Company Overview
• BMR Process Flow
• Frameworks - I C Systems
• Advanced pH Controller

3
Company Overview

• Impala Platinum second largest platinum producer
  in world
• Produce 2.0 million ounces of platinum annually
• Produce copper, nickel and cobalt as by-product
• Generate annual income of R 1.5 billion from base
  metals
• General platinum process overview

4
BMR Process Flowsheet
MATTE GRINDING
MATTE FROM MINPRO
NICKEL LEACH
COPPER LEACH
PGM CONC LEACHING
PGM CONC DRYING
DESPATCH TO PMR
NICKEL PURIFICATION
COPPER PURIFICATION
COPPER ELECTROWINNING
COPPER PRODUCT
NICKEL REDUCTION
COBALT STRIPPING
COBALT PURIFICATION
COBALT PRODUCTION
SAMPLE QA PACKING
NICKEL POWDER WASHING/DRYING
AMM SULPH PRODUCTION
SAMPLE QA PACKING
BRIQUETTING SINTERING
SAMPLE QA PACKING
SALES
5
Frameworks - Information Control Systems
6
Human
Human
Source Butler M, ISM - USB
7
Human
8
Advanced pH Controller in First Stage Leach -
Feedback
9
Process Description
10
The Process Problem

• Fe is an impurity. Sometimes gt1 in matte.
  Needs to be removed in first stage otherwise
  continues through PGM circuit causing filtration
  problems
• Ni (/- 47 in matte) extracted in first stage
  process
• Need to ensure high Fe and Ni extraction
  efficiencies
• Improvement of PGM grade
• How do we achieve this?
• Control pH

11
pH Advanced Controller Principles

• Stabilise pH to improve leaching efficiency of Fe
  and Ni better quality of PGM concentrate
• High pressure acid leach has complex reaction
  kinetics
• On-line pH sampling
• Simplify control approach. Manipulate acid
  addition to compensate for
• Pulp density changes, Product feed rate changes
• pH response measurements
• Advanced controller based on a hybrid of fuzzy
  logic technology and fundamental principles

12
APC Design

• Disturbance variables
• matte composition, spent electrolyte solution
  composition, pulp feed rate
• State variables
• pulp density, Cu in solution
• Adjustable variable
• spent electrolyte flow rate
• Target variable
• ph in first compartment

13
Sampling and Measurement
14
APC Solution
15
APC Performance
16
APC Results

• PGM concentrate grade is better i.e. Less Fe and
  Ni slippage
• Performance analysis conducted in March 2007
• pH variation reduced from 1.2 to 0.7 (an
  improvement of 40 in pH stability)
• Ni extraction efficiency increased by 0.5 to
  91.7
• Fe extraction efficiency increased by 3.3 to
  88.5
• Increase of PGM grade by 1.4

17
APC - Challenges

• Low throughputs pH control not as good which
  presents opportunity for controller improvement
• Change management
• People
• Training
• Work Procedures
• Controller and process performance monitoring
• SLA controller maintenance and performance
  audits

18
APC Challenges Overcome
19
Thank you