PASTE & FILTERED TAILINGS
Operation support - your partner on the pastefill journey
Filling the void between paste engineering and operations
Paterson & Cooke ’ s Rob Brown and Maureen McGuinness discuss the evolution of the paste backfill Expert-Owner relationship
Paste backfill ’ s profile is on the rise again as tailings storage headlines make the news . Traditionally a paste backfill project followed a very linear trajectory ; concept , test , design , construct , repeat . Occasionally , a paste expert would return to troubleshoot or expand a system , but usually the relationship had served its purpose and both parties moved on .
Recently the roles of Engineer , Vendor , Constructor and Operator are blending together , and it has become more obvious than ever that the Expert-Owner relationship is unique and valuable ; one that should continue beyond start-up and into years of successful operation . Experienced paste engineers are hard to find , and so there is a great need for Owners to rely on help from a deeper talent pool of shared resources through a flexible contract that guarantees sustainable long-term operating expertise .
The backfill void
Paste projects have been going on since the late 1990s when Dave Landriault et al focussed a team of people on spreading the paste gospel and bringing the technology to the masses . Fast forward 20 years and the majority of projects still progress along those same lines ; concept development , test work , feasibility / basic / detailed
Paterson & Cooke Directors Rob Brown and Maureen McGuinness design and construction . But only recently have Owners started retaining the services of the original designer to maintain , operate and / or expand their original system . One of the authors of this article experienced this phenomenon when she called the designer of the paste plant she had inherited and was told that this was the first time
“ It should not be harder to fill the hole than it was to make the hole !”
that a mine had kept in touch with them after commissioning was over . At that point , she knew there was a void in the support networks offered by design firms or asked for by mining companies .
The Expert-Owner relationship historically has been punctual . A secondment of a backfill engineer provides a short-term solution that often ends with the mine hiring the engineer outright . Most commonly , an engineering consultant visits the site and provides a report with recommendations . But , in too many cases , with production taking priority or no backfill department to execute the work , little progress is made .
From a frustrated miner
The backfill helpline
The authors have seen a dramatic increase in demand for paste engineers , to the point where contracts are now written to include the provision of on-going technical support and advice to the local operators on an annual basis . The open
contract can allow for a safety net at the end of a phone line , but it becomes very ad hoc , sometimes too late , and always without structure . A more proactive way is to set out a long-term plan which include goals and a timeline .
A Backfill Management Plan is a leading example where a systematic approach can be quickly transferred to a site , just like a corporate safety management system . The basic components are common to most pastefill systems , with the details being adapted to reflect the unique requirements and structure of the site . It includes components such as paste stope design , hydraulic modelling , strength requirements , procedures , training , QA / QC and production tracking . There is great value in saying upfront that we expect a lot from our backfill department , no less than our development crews or production team , and providing the tools and support to meet those expectations .
Backfill Management service covers liaising between the mill and the mine , establishing the system components with the Owner and helping with the incorporation of the plan into daily operation . It includes continuous improvement such as binder optimisation programs , barricade monitoring and maintenance planning . With a Backfill Management system in place , the on-going Expert-Owner relationship is then founded on a common understanding of the site expectations , opportunities and constraints .
There are signs that the mining industry has recognised the value of planning the operation stage with as much consideration as the design stage of the project . Recent bid packages for Engineering & Supply of paste systems are now including scope for long term operations support where the engineer is retained on multiyear deals to provide technical support , to train and teach , to log and interpret data , optimize backfill costs , and to oversee expansions .
The people
Many consultants now make a living by providing " after-market service " for paste operations . Owners without internal paste resources bring in experts to create structure , procedures and policies that manage the backfill process to a higher standard . These pastefill experts have similar operational experiences and understand the challenges of day-to-day pastefill production . This allows the Owner to quickly tap into a wealth of pastefill operational experience and leapfrog over months or years of trial and error when setting up a new system to keep the pastefill operation running effectively .
It takes a certain type of person to step in and help with paste engineering on site . Passion helps . As does patience in the face of the realisation that
P10 International Mining SUPPLEMENT | APRIL 2023