****This article was first published by Rob Bush on the 5th of January 2018 on Linkedin.
The years where economies of scale dominated the mining optimisation and profitability discussion have come to pass, and the new initiative on the scene is optimisation to reduce operating expenses (OPEX). The mining industry is also facing intense internal and external pressure to be ever-better stewards to the communities they serve by improving health and safety standards, and reducing the carbon footprint of their operations. Considering that ventilation represents 25-40% of a mine’s total energy consumption (Dept of Mining, Queen’s University – Canada), and almost universally there is very little optimisation of ventilation systems in the industry, it would seem natural to explore how systems may be deployed to answer both the OPEX and stewardship demands. Recognising these arising needs in the mining industry, Howden has strategically positioned over the last 3 years to be able to provide solutions to an industry hungry for improvement. The acquisitions of Simsmart Technologies, as well as Chasm Consulting, creator of Ventsim, the world-renowned ventilation modelling software, are tangible moves that have been made to allow Howden to serve up both the turn-key solutions and the expertise the industry is looking for.
By now the majority of mining ventilation specialists would have heard the term Ventilation-On-Demand, typically dubbed VOD. It is possible that a significant contingent of this group also may be tired and sceptical of this concept after years of being overwhelmed by its promises and underwhelmed by the short-comings of its execution in the field. Howden recognises this scepticism, and has made a concerted effort not only to reverse the scepticism but to deliver more than what VOD promises. Summed up in few words, VOD describes an automated system in which the clean air needed to safely and effectively work in an underground area is delivered only to the areas where presence of vehicles and personnel demand it. In this way, a mine can reduce their total air requirements, thus reducing the energy input to the fans. Since monitoring the work area's vehicle and personnel presence, airflow, temperature, and gas levels due to diesel exhaust or blast fume are all required to be able to deliver the appropriate quantity of air, the guarantee of safe working conditions for the personnel in the work area is intrinsic to the system. Achieving VOD as described here is no small feat in and of itself. Many operations have struggled to integrate asset tracking systems with SCADA control, while programming the implications of that tracking system into ventilation control systems. It is something easier said than done, without doubt.
Backed by more than 20 years of development in not only mining, but also industrial and military applications, Howden offers advanced ventilation control strategies that not only deliver according to real time air requirements, but also optimise the use of ventilation infrastructure to ensure the minimum consumption of energy possible. The computational engine continuously solves the system of equations of the mine ventilation network in real-time. A simplified example is seen in the comparison of two different operating scenarios on a mine level in Figure 2. For clarity, Figure 1 shows the 3D configuration of the area seen in Figure 2. This highlights the use of "Speed Optimizer" A proprietary advanced control strategy.
As can be seen both situations deliver the required air for the two occupied working areas. However, for the scenario on the left it can be seen that the work area requiring the most flow has an 80% damper opening, and the fan is operating at a much lesser speed. In fact, by reducing the fan speed by one half, an 88% reduction in power consumption is achieved. The system is thus minimising mine resistance to allow for a reduction of fan speed, all in real time. Once these kinds of optimisations are realised throughout an entire mine, the total air demand of the mine may decrease by more than 30%. This reduction is then considered for the surface fan speeds as well, their speeds are also automatically reduced accordingly, thus generating energy savings of more than 50% mine wide. Fan Law 1 gives us this convenient exponential relationship between fan speeds and power consumption (The proportion of reduction in speed results in a power consumption of that same proportion to the 3rd power).
Currently, only a small number of mines in the world have adapted this new breed of ventilation technology/methodology. There is a natural tendency of slow technology adoption in the mining industry, and it seems correct to estimate that this is due to the harsh mining environment that emerging technologies must be able to withstand. The scepticism behind slow adoption rates is well-founded, thus the real problem to be solved is achieving excellent durability and adaptability for mine ventilation automation technologies. Howden recognises this problem and has confronted it with a few key system features:
In addition to overcoming the questions of durability and adaptability, these same features answer another important challenge for miners: implementation. The plug and play functionality of the system reduces installation and integration times significantly by removing the need for any on-site automation programming. All system functionality comes pre-installed on every PLC panel, therefore the level of automation desired is simply enabled. The only remaining custom integration to be done is integration with existing support systems such as fan’s VFDs and Starters, third-party tracking systems, or existing PLC controls. These integration times vary on a case by case basis, but the end goal is to remove the need to “rip-out and replace” automation already on-site. This is why Howden’s ventilation automation solution is both plug and play within its own family of automation hardware, but also able to be programmed onto existing ventilation controllers.
The mining industry is now poised to move into a new age of ventilation control that mimics the HVAC controls that are considered a standard part of our daily, above ground lives. Smart adaptation to real time ventilation needs will one day be a standard for the mining industry, it is only a question of overcoming the aforementioned challenges. For some mine operations, these challenges have already been solved, resulting in reduced carbon footprints, significant energy savings, and a step-change in monitoring and guaranteeing a safe work environment for the miner. Does implementation, integration, and site education require some time and effort? Absolutely. Is the payoff of health and safety improvements, $2-5M annual energy savings, and potential productivity improvements worth it? It's certainly worth a detailed analysis. Get in touch to see how Howden can help you determine how to optimise your mine's ventilation system.
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