Short Course

Heap Leaching for Managers - Professional Mining Course

Short Course

Heap Leaching for Managers - How to Enable a Successful Heap Leach Operation

Date: Sunday, October 19
Time: 8 AM - 5:30 PM
(5:00 - 5:30 PM extended discussion session)
Event Concluded

Course Overview

Heap leaching is an established technique for making a profit from the exploitation of ores of gold, silver, copper, nickel and other metals. It is often considered a less desirable alternative than more capital intensive processes such as leaching in agitated tanks, but in reality it can yield a higher return on invested capital and is often the better choice. This short course attempted to clarify some of the technical concepts that are important in choosing the right process.

Expert-Led

Industry professionals with decades of experience

Interactive

Discussion periods and Q&A sessions throughout

Who Attended

This year's conferece was of interest especially to corporate planners and project developers, but also discussed technical details of interest to regulators, academics and students.

Primary Audience

  • Corporate Planners
  • Project Developers
  • Mining Engineers
  • Process Engineers

Also Beneficial For

  • Regulators
  • Academics
  • Students
  • Mining Consultants

Course Agenda

Morning Sessions (8:00 AM - 12:30 PM)

8:00 - 8:30 AM: Introduction (Kappes)

  • • History of heap leaching - How many heap leaches? What percent of metals do they produce?
  • • Recent trends towards lower grade heaps, and finer (HPGR) crushing
  • • Examples of the extremes - height, cold climate, high rainfall; low and high grades

8:30 - 9:30 AM: Lab Testing (1 Hour) (Kruth)

• Procuring Representative Samples

  • - Interaction between geologists and metallurgists is really important
  • - Has the drilling method affected the validity of the samples?
  • - Don't ignore variation in ore types - some rocks are higher in clay than others; type and amount of sulfides is important to know

• Lab testing to identify the important design issues, especially in regard to Run-of-Mine or coarse-crushed heaps

• Projecting lab results to field recoveries

9:30 - 10:00 AM: Assessment of Ore Permeability (Milczarek)

  • • Ore type and processing drive permeability
  • • Lab testing for permeability and construction methods to ensure permeability
  • • How to select individual lift height and total heap height
  • • Agglomeration - When should it be used?
10:00 - 10:15 AM: Refreshment Break

10:15 - 11:15 AM: The Correct Corporate Philosophy is Critical (1 Hour) (Kappes)

• Engineers should not be selected on study cost but on experience

• Capex does not usually drive a heap leach project. So, don't push for a low capital cost in the study. Examples of where low capital cost leads to bad decisions:

  • - Crush size too coarse
  • - No agglomeration
  • - Use of preg and barren tanks rather than ponds
  • - Lack of an adequate on-site laboratory
  • - Inappropriate stacking systems (methods)

• Financing challenges for the minerals processing industry, and how selection of a heap leach versus an agitated leach, might be the right choice

11:15 - 11:45 AM: Discussion Period

Comments, questions, and answers on the issues presented so far

11:45 AM - 12:30 PM: Chemistry & Dynamics of Gold Heaps (45 Min) (Kruth)

  • • The problem of copper in gold heaps - new chemistries, especially involving glycine
  • • Does cyanide level make any difference?
  • • How to ensure the heap does not go acidic
  • • Does solution flow meet a "plug flow" model?
  • • How to model solution flow in multi-lift heaps

12:30 PM - 1:15 PM: Lunch Break

Networking opportunity with fellow professionals

Afternoon Sessions (1:15 PM - 5:00 PM)

1:15 - 2:15 PM: Acid Heap Leaching for Copper and Nickel (60 minutes) (Seal)

  • • How to establish or ensure solution permeability
  • • Is oxygen always necessary?
  • • How to ensure correct flow of air in the heap?
  • • The importance of leachable impurities, especially magnesium
  • • Enhanced copper recovery with novel activation processes

2:15 - 3:15 PM: Heap Leach Closure (60 minutes) (Milczarek/Parshley)

• Begin with the end in mind:

  • - What will the long-term drainage chemistry be
  • - Slopes designed to reduce final grading costs
  • - Cover systems to reduce post-closure net infiltration
  • - Assessment of potential for long-term acid generation

• Surface design and water management

• Active management/inventory reduction

• Long-term drainage management

3:15 - 3:30 PM: Refreshment Break

3:30 - 4:00 PM: Siting & Shape of the Heap (30 minutes) (Kappes)

• Don't end the heap on a steep slope or narrow valley

• Heaps with large volumes but small top surfaces are not ideal

  • - Gold inventory is large and difficult to wash out
  • - Sideslope management is complicated
  • - Heaps can conform to lots of different topographies

4:00 - 4:30 PM: Economic Considerations (30 minutes) (Kappes)

  • • Heap Leach or Mill? Or both?
  • • What is allowing the very low grades currently being looked at?
  • • What can we expect of a heap leach economic (production) model?

4:30 - 5:00 PM: Extended Session

Discussion period (30 minutes): Comments, questions, and hopefully answers

Course Coordinators and Presenters

This course was coordinated by Kappes, Cassiday & Associates (KCA), one of the premier firms in the industry. KCA have been designing and building heap leach projects for fifty years.

Presenters included:

  • Dan Kappes, Founder and President, Kappes, Cassiday & Associates
  • Dave Kruth, Lab Manager, Kappes, Cassiday & Associates
  • Mike Milczarek, President, GeoSystems Analysis, Inc., USA
  • Jeff Parshley, Corporate Consultant, SRK Consulting (U.S.), Inc.
  • Thom Seal, Professor, University of Nevada, Reno