TESTIMONIAL & PAST CLIENTS

As lead consultant for Codelco, Steve was responsible for the test program, strategic commissioning and comparison of 3 pilot paste thickeners. FLSmidth, Outotec and Delkor paste thickeners were run in parallel to verify the unit area loadings, residence time, bed depth and overflow quality. As the pilots were run differently, a means to fairly compare the vendor results made this project all that more interesting.

Each of the vendors had a different method to calculate unit area or flux rates. As thickener consultant the scope included the following:

1. Confirmation of paste thickener sizing and comparing the vendor results
2. Selecting the right pump and pipeline to transport the different rheological paste.
3. A review of the vendor recommendations

Anomalies that were addressed during the test program were:

• The effect that pH has on the underflow yield stress.
• Running the pilot thickeners to hydraulic overload – maximum compression.
• The importance of dilution water addition and how this can have a detrimental effect on a small pilot unit.
• The understanding of pilot limitations i.e. does the physical height of the pilot thickener, permit high unit loadings and high residence time to operate simultaneously?
• The underflow yield stress is significantly different between a pilot plant compared to an installed paste thickener. This had a huge impact on pumping velocity .

There was some concern over the high dosage of flocculant for two stage thickening. Alternate strategies were suggested to lower capital costs. The project was approximately 3 months in duration.

Consultant for the EPCM of a tailings dewatering plant. The study included a review of different dewatering options to remove fine hydrotalcite from the tailings. Equipment included thickeners, gravity drainage deck, belt filter press, centrifuges, secondary flocculation and geotubes.

The high level study highlighted all the pros and cons of the various options. Based on the report, Rio Tinto went ahead with the EPCM for the installation of three “thickener type” gravity drainage decks followed by three belt press filters.

As the consultant for the project, the plant layout, design and specifications were completed under my guidance. The project was approximately 10 months in duration.

A review was conducted on a Fluor 2008 Feasibility report. Based on this review a preliminary design basis for tailings dewatering, transport and deposition systems was developed. Short fall/gap analysis was undertaken on available information / data / testwork which would help the development of an optimized tailings design.

A number of recommendations were provided to overcome the gaps.

The client also requested a plan for further test work for a full characterization of the tailings and system designs for de-watering, transport and deposition.

BHP utilised his dewatering experience in Enhanced Tailings Disposal (ETD). This is the re-flocculation of thickener underflow via the addition of a modifier (chemical) immediately prior to the tailings discharging into the tailings storage facility (TSF). ETD can be applied to single or multipoint discharges into existing TSF or into Tailings Cells, where the flocculated, settled and dewatered tailings are loaded into trucks using an excavator and dry dumped with either refuse spoil or coal rejects.
BMA Saraji Mine commissioned Steve to review the advantages and disadvantages of ETD and provide advice on further trials of ETD at Saraji Mine. A complete capital and operating expenditure for both a pilot plant and a fully functional large tailings plant for fine reject discard was completed.

The report highlighted a number of reasons and risks associated with secondary flocculation – including the risks associated with high polymer dosages and desiccation in the Tailings Storage Facility. It also reviewed the density achieved under confirmed solids stress.

A holistic approach to Secondary Flocculation was required. This considered solid liquid separation design, pumping systems, deposition systems as well as impact on overall plant water balance.

The scope of work included the review of all the Shell Albian Sands thickener pilot plant and pumping results. The review looked at different technologies and flow sheets to dewater the coarser sands produced at the Albian Sands, Muskeg River Process Facility. Paste thickening results were analysed and in conjunction with cyclone test results, a flowsheet was designed with a co-disposal system.

A means to change the chemistry of the slurry to assist pumping was addressed. While all clays are negative, a system to coagulate and change the particle charge was addressed. The project also compared remote site locations to current plant location for lower cost alternatives.

The project involved commissioning and upgrading the Saprolite and Limonite Beneficiation thickeners. Operations had experienced paste handling, thickener density and pump problems with high yield stress material.

The commissioning included numerous concepts to overcome the design of the control and slurry environment. A total of 19 anomalies in the installation, design and operating procedures were highlighted.

The Counter Current Dewatering (CCD) Thickeners Review Study involved reviewing all aspects of the 6 thickeners in order for the plant to achieve a 20% increase in throughput. The review involved analysing settling test data reported by FLSmidth and Outokumpu. The current thickeners were analysed with a view to produce higher underflow solids.

A review of the drive mechanism was undertaken with respect to torque, speed, scaling and availability. Capital and return of investment costs for the addition of 1-2 thickeners were completed. The study involved reviewing the pumping capability of the current system. Each of the underflow and overflow lines was modeled using AFT Fathom software. A presentation of the results was made to the operations staff.

A CCD software program was designed that reviewed the washability of the system and the return of investment for additional thickeners.

Completed the Design Criteria, Process Flow Designs, Piping and Instrumentation Diagrams and Operating Procedure for a 17 500 t/h thickener tailings paste plant. Part of the project was spent gathering data from the FLSmidth and Outotec Paste Thickeners located on site at Escondida.

The application involved “rethickening” thickener underflow flotation tailings from 48% solids to approximately 65% and recovering as much water as possible. Data from FLSmidth and Outokumpu, whom both size thickeners differently, was analysed in order to generate a fair comparison. The underflow solids then underwent pump loop tests followed by deposition and flume box testing.

The entire plant layout and design was modeled exactly according to my concept and specifications. Numerous presentations were made to BHP substantiating the process, control and design philosophy. Issues that were reviewed included, yield stress limitations, maximum thickener drive torque, above ground versus in ground thickeners, PD versus centrifugal pump selection (where to draw the line) and means to reduce flocculant. The project was approximately 6 month in duration.

Over 70 sizing calculations were completed for the design of a 54 000 TPA nickel refinery. Numerous Process Flow Diagrams and Process and Instrumentation Diagrams were completed. Specifications, scope of work and datasheets for each piece of equipment were finalized. Purchases were made with the technical accepted vendors.

Steve was promoted to lead the Mechanical Engineering for Area 370 and 380. Over 188 mechanical items were modeled in a building covering 120 m long by 18 m wide, over 35 m tall. 3D modeling was conducted using Bentley Navigator 2004. During this time, Steve successfully commissioned two 2500 m3 Storage Tanks and a 23 m diameter Nickel Thickener.

Completed numerous tailings settling tests, sized, purchased and commissioned a 60 ft copper concentrate thickener; selected peristaltic pumps for thickener underflow solids and sized pipeline.

As the senior metallurgist ensured that the layout was practical and that a system was used to measure the volumes and tonnages reporting to the filters.

Offering dewatering technical support to approximately 30 Sales Engineers worldwide. Territories included Europe, Africa, Australia, Middle East, South America and China. Part of my responsibilities was training Sales Engineers on various aspects of mineral dewatering, classification and thickening. Primary applications of responsibility included coal, potash, oilsands, kaolin and soda ash. Test results were analysed and with the client involvement, flow sheets developed. A total of 7 years were spent with FLSmidth.

The project involved a confidential process in which fine bituminous and oxidised coals were recovered. Heavy oil was emulsified and fed into the conditioner at 10% solids by weight fine coal.

As lead Process Engineer, I was responsible and accountable for the interpretation of the testwork and subsequent sizing and selection of the process equipment, including conditioning, flotation, tailings thickener, belt press filters and associated equipment.