Alex G. Doll, P.Eng


Mineral grinding specialist.  Provider of software and mathematical modelling consultant for grinding system design, bench-marking and optimization.

Metallurgical sample collection program design and execution for scoping and feasibility studies.

Plant audits of operating mills for process improvement.

Training of engineers and operators in comminution circuit operations and optimization.

Significant programming experience in process modelling and material balance calculations.


ALEX G. DOLL CONSULTING LTD. (2000 - present)

Independent consultant providing process engineering and computer consulting to the mining industry.  Actively involved in technology transfer by providing short courses and guest lectures on grinding modelling and geometallurgy.

Performing grinding system design, peer review studies, supervising laboratory test programs, and operating plant optimization studies.  Recent work includes:

Debottlenecking and plant audits performed at mines in BC (2019), Detour Gold (2018), and Mount Milligan (2017).  Conceptual design studies for projects in Chile (2019), Serbia (2018), Nova Scotia (2018), and Quebec (2018).  Design peer review studies in USA (2016), Perú (2015), and Chile (2015).

SAGMILLING.COM Comminution web site (ongoing)

Developer of "the Internet's first comminution resource" at Web site contains a collection of both free and subscription-based calculation tools to aid metallurgical process engineers perform comminution calculations. The online library of technical articles contain several papers on metallurgical topics including comminution modelling, mass balance calculations and laboratory comminution testwork program information.

REGISTRAR AND WEBMASTER Fifth, Sixth and Seventh International Conference on Semi-Autogenous and High Pressure Grinding technology (2011, 2015 & 2019)

EXECUTIVE EDITOR XXVII International Mineral Processing Congress – IMPC 2014 (2013-2014)

One of three executive editors for the IMPC 2014 conference held in Santiago, Chile.

GRINDING STUDY CONSULTANT DJB Consultants Inc. (2006-2012)

Consultant to a senior grinding system specialist performing detailed calculations, data analysis, testwork program development and supervision, and geometallurgical model creation for comminution studies. Studies include conceptual through feasibility to detailed design and auditing of existing milling circuits.

PEBBLE PROJECT Northern Dynasty Minerals (2005 - 2006)

Project engineer performing project management and process engineering for the owner's team of a 220,000 stpd copper-gold porphyry feasibility study. Duties include supervision of multiple engineering contractors; developing project budgets, procedures and policies; and ensuring technical continuity at interfaces between different contractors.


Process engineer performing material balance calculations and system database development for a froth treatment capacity expansion study.

CNRL HORIZON OIL SAND PROJECT Colt Engineering (2002 - 2003)

Process engineer involved in feasibility study for a 270 kbpcd oilsand mine. Duties include material balance calculations for bitumen extraction and froth treatment process options and support of unit operation selection trade-off studies.

MUSKEG RIVER OILSAND PROJECT Fluor/Muskeg River Contractors (2000 - 2001)

Process engineer responsible for designing a groundwater collection system including seven wells and a network of approximately 15 kilometres of pipeline.

FLUOR DANIEL Mining & Minerals (1992 - 2000, 2003 - 2004)

Metallurgist involved with project work, feasibility studies, computer development, engineering proposals and operator training systems. Projects included base metals concentrating, smelting and refining, gold leach plant design, pyrometallurgical plant basic design, creation of computerized tools for metallurgical design engineering and writing computerized plant operator training manuals. Responsibilities included process flowsheet development, equipment sizing and specification, project feasibility cash flows, computer programming, database development and technical writing.


English- Fluent; Spanish- Functional; French- Reading ability


B.A.Sc., Mining and Mineral Process Engineering, University of British Columbia, 1992

Short Course Instructor

Short Course on Comminution & Semi-autogenous Grinding

Presented on five occasions including to the public in Canada & Perú and to private customers in Canada, (2018-2019).

McGill Mineral Processing Short Course

Presented the “AG/SAG milling” module (2017, 2019), Montréal, Canada.

Geometallurgy basics

Short course presented in association with Target Rocks (2017), Lima, Perú.
Private short course presented to a mining client (2015), Cajamarca, Perú.

Bond-based Grinding Models for Design and Geometallurgy

Short course presented at the Canadian Mineral Processors AGM (CMP 2014), Ottawa, Canada.
Short course with co-presentor Peter Amelunxen presented at Procemin 2013, Santiago, Chile.

Professional Associations:

Trustee, SAG Conference Award Foundation;
Member, Bond Grinding Circuit Efficiency working group, Global Mining Guidelines Group;
Member, Canadian Institute of Mining and Metallurgy, Australasian Institute of Mining and Metallurgy, and
Member, American Institute of Mining Engineers

Peer reviewer, Minerals Engineering technical journal;
P. Eng., Association of Professional Engineers and Geoscientists of BC;
Executive Committee Member, Vancouver branch, Canadian Inst. of Mining, Metallurgy & Petroleum (1996, 1998, 2001, 2004-2012; Webmaster 2007-2012);
Branch chair, Vancouver branch, C.I.M. (2008);


"A simple method of assessing ball mill health using Bond tests and Functional Performance"
co-authored by A. Morneau, J-F. Dupont (Detour Gold Corp) and D. Michaud (911 Metallurgy)
presented at the 52
nd Annual Canadian Mineral Processor’s Conference, 2020 in Ottawa, Canada.

"Bond's work index: What it is and what it isn't"
co-authored by Berge Simonian (Centerra Gold – Mt. Milligan mine)
presented at the SAG 2019 Conference in Vancouver, Canada.

"Designing an optimal comminution sampling program for geometallurgy"
presented at the 14th Int. Mineral Processing Conference (Procemin-GEOMET 2018), Santiago, Chile.

"Power-based modelling of single-stage AG and SAG mill circuits"
co-authored by Miguel Becerra (Anglo American T&S)
presented at the 13th Int. Mineral Processing Conference (Procemin-GEOMET 2017), Santiago, Chile.

"Five mineral technologies we should be using more of in British Columbia"
presented at the 2017 CIM South-Central Branch AGM & Conference Kamloops, Canada.

"Fine Grinding, A Refresher"
Presented at 49th Annual Canadian Mineral Processors Operators Conference, 2017 in Ottawa, Canada.

"A public Database of tumbling mill grindability measurements and their relationships"
presented at the 12th International Mineral Processing Conference (Procemin 2016), Santiago, Chile.

"An updated data set for SAG mill power model calibration"
presented at the XXVIII International Mineral Process Congress (2016), Quebec City, Canada

The engineering and process effects of choosing a motor design speed”
co-authored by Kurt Tischler, Process Industries and Drives, Siemens AG
Presented at the SAG 2015 Conference in Vancouver, Canada.

"A simple estimation method of materials handling specific energy consumption in HPGR circuits"
Presented at 47th Annual Canadian Mineral Processors Operators Conference, 2015 in Ottawa, Canada.

"A comparison of SAG mill power models"
Presented at Procemin 2013 conference in Santiago, Chile.

co-author "Mineral Slurry Pipelines for Rugged British Columbian Terrain"
Primary author: Brad Ricks, Brass Engineering International
Presented as the CIM Maintenance MEMO 2013 conference in Kamloops, Canada.

"Grinding: Why So Many Tests?"
co-authored by Derek Barratt, DJB Consultants, Inc.
Presented at the 43rd Annual Meeting of the Canadian Mineral Processors, 2011 in Ottawa, Canada.

"Microcracking versus the Phantom Cyclone; Comparing SAG Mills and HPGR on a Consistent Basis",
co-authored by Derek Barratt, DJB Consultants, Inc. and Ricardo Godoy, Anglo American Norte.
Presented at Procemin 2010 conference in Santiago, Chile.

"Case Studies on the Effect of Sample Dimensions on Comminution Testwork Results.",
co-authered by Derek Barratt, DJB Consultants, Inc.
Presented at Procemin 2009 conference in Santiago, Chile.

"Testwork Programs that Deliver Multiple Data Sets of Comminution Parameters for use in Mine Planning and Project Engineering",
co-authered by Derek Barratt, DJB Consultants, Inc.
Presented at Procemin 2008 conference in Santiago, Chile.

"Solving Mass Balances using Matrix Algebra",
Published as part of the AusIMM Mineral Processor's Toolkit.

"Comparison of UCS to Bond Work Indices",
co-authored by Derek Barratt, DJB Consultants Inc, and Ken Wood, Fluor Mining & Minerals.

"Performing Metallurgical Calculations on Computerized Spreadsheets"
Published to Internet, Apr 3, 2000  

"Summary of the Australian PAL Nickel Projects"
Presented Nov 1999 to the Vancouver Branch of the CIM.

"Refractory Gold Autoclaving".
Presented April 1999 to the Perth Branch of the Australasian Institute of Mining and Metallurgy.

"Driller - An educational simulator",
co-authored by Dr. John Meech, UBC. Presented September 1993 at the CIM District 6 Meeting, Vancouver.


Address: Box 1236, Logan Lake, BC, V0K1W0, Canada
Mobile Phone/Whatsapp: +1-778-388-2444