Steve Franklin, founder of Eltirus, looks at some factors that influence quarry sustainability for Quarry Magazine.
What does it mean to sustainably extract a quarry deposit? One of the best definitions I have seen is, “for a sustainable initiative to be meaningful, it must be environmentally and socially beneficial as well as economically viable.”
But what does that mean in practice?
You only get to know what’s in the ground through geological investigation and modelling.
Drilling, sampling, face mapping and other data, brought together in geological modelling tools help to provide a clear picture of what materials are in the ground and where they are, creating an ‘inventory’ of what’s in the ‘rock warehouse’, it’s quantity and location.
Unlike a conventional warehouse where we know we have 1,000 units of product XY in aisle six, level five and can direct a forklift operator to move them from storage to despatch, the ‘rock warehouse’ is not like this. Instead of being stacked in shelves that allow access to items stored at any point high or low, we need to uncover items from top to bottom, hence the need to have a clear idea of their location, also realising that the materials at the top, are generally the lowest quality as well.
This knowledge helps us plan a quarry from scratch and better understand an existing one – it is the one factor that we cannot change.
Market, sales and pricing
It’s one thing to have a potential quarry deposit, it’s another thing again to have a market for it and one without the other is rarely workable. It’s almost as if there are two types of exploration required – one to find the deposit and the other to find and understand the market.
If you take the time to understand both deposit and market (including the prices customers will pay and what the consumption is), you can determine the value of extracting that particular deposit and how best to maximise its value.
Interestingly, we see few companies that work specifically on quarry market research and pricing, TKB being the only one that immediately comes to mind.
What we do know is that where a systematic approach to understanding what customers will buy, in what quantity, when and for how much, this information can dramatically improve planning and operational viability.
What can we do with our newfound deposit and market knowledge? How do we leverage this new information to make the most of it? As the quarry operator, you need to know how best to extract the deposit is such a way as to match your production with market demand and you need to do this in a fashion that reduces your extraction costs and maximises the sales price.
The way to achieve this goal, is by using deposit optimisation tools such as Deswik.GO which are used to bring together practical extraction rules, operational costs, market and deposit data to determine what the optimal approach is to extraction.
Once these models are set up, they are easy to update and adjust to ensure that you have a dynamic approach to planning and budgeting. For example, if you know a big fill job was coming up, you could run the model to satisfy add this requirement and see where the best places to extract would be.
Likewise, if you were assessing a different haulage method (conveyor, electric, etc) you could program in the capital requirements and change in operating costs to determine what the impact would be on the bottom line.
By bottom line, I mean the Net Present Value (NPV) of the operation, but you can also optimise for other things, like emissions.
A further step is to optimise a cluster of quarries. By this I mean that you could optimise three to five quarries simultaneously against the known major projects and demand likely to occur in the next five years to help understand which quarries should be developed and when to maximise the NPV of the cluster.
A good optimisation model is the place that your data comes together in such a way that you have confidence in how best to extract deposits and how to quickly adapt tochanging circumstances.
Operational scheduling and planning
One of the truly useful things that we get out of the optimisation process is stage shells that help us with our short-term, detailed planning for how to extract the deposit. Without the use of an optimisation tool, the creation of extraction stages is at best “arbitrary” and often results in “pretty pictures” that have no real bearing in how the deposit will actually be extracted.
The conventional approach to the creation of stage shells (if they are to be truly representative) is highly iterative and can soak up engineering hours, to the point where compromise is the only real outcome.
The use of optimisation tool stage shells ensures that there is an effective basis for accurate medium-term planning that ensures that value identified in the optimisation process is not lost in poor or absent operational planning and control.
In short, it gives you a ‘real’ plan to judge actual vs. predicted performance against. Interestingly we are also seeing an increasing interest in this operational planning process from regulators and company auditors, both of which are interested to see a structured approach that factors in the key variables.
One of the outputs that a good scheduling and planning process can give you is accurate estimates of mobile equipment hours. Most medium-term scheduling models can be run in such a way as to determine the likely loading tool and hauler hours to achieve the schedule. In fact, depending on the level of detail that you want to add, the models can detail out pretty much all the operational requirements from drill and blast, clean-up, extraction and through to rehabilitation planning with a good degree of accuracy. Use the mobile equipment that you have in the most efficient way possible. By this I mean, the right amount of equipment at the right time and working at the correct rate.
Yet again, if we are estimating this as part of our planning process, we then have something to compare with – in essence, the Plan – Do – Check – Act of quality control. Note however that if you don’t have the tools or methodology to Plan, then you can Do, but there is only historical performance to Check against and no way to know how (or if) your operations need to Act in a different way.
Where we see real opportunity is to budget not just for equipment operating hours, but to also budget for emissions as well.
Checking equipment operating hours and particularly idle hours is particularly important for as long as a site is running diesel powered equipment. Every hour that a machine is idling, it is consuming fuel, running up a maintenance bill, reducing its resale value and producing unnecessary emissions – none of which is helpful.
A further area for investigation in terms of planning is to look at the fuel consumption of older generation equipment vs. new machines to determine what the impact of this is on fuel consumption and emissions.
By way of example, a Cat 773B (1986) with a rated payload of 45t has a fuel burn of 25 – 69 litres per hour, vs. a current model 775G (2019) with a rated payload of 64t and a fuel burn of 24 – 47 litres per hour. While it may seem that the older truck is “cheap to run”, the reality can be very different once you sit down and look at all the factors in the owning and operating cost equation.
Experience shows that sustainable operation is not just good for the environment, it is good for the bottom line as well. Take the time to put in place the knowledge and systems that allow you to ensure that you can Plan – Do – Check – Act to maximise operational value and improve sustainability. •
Visit eltirus.com to learn more.