(2) Broken Stocks Management

Follows on from (1) The Broken Stocks Saga.

The first learning for me related to the broken stocks. The importance of these in achieving target qualities for each stockpile construction can not be understated. If you provide the grade controllers with a set of broken stocks that are close to quality specs, you make it relatively easy for them to hit their target. On the other hand, provide them with a set which has one or more qualities a long way off spec and you make it extremely difficult. Similarly, provide a large quantity of broken stocks and you provide more choice, provide a small quantity and even though they might be at average spec, the lack of choice (and therefore scheduling flexibility) may make it difficult to achieve target.

So whereas the short term planning group were planning the shovel excavation for the next month, I believe a much better solution would be for them to manage the broken stocks instead. The precursor to planning is to determine the quantity and quality target bands that will provide sufficient capability to meet necessary targets. The planning process then involves determining what the starting broken stocks (quantity and quality) are and then assessing which blocks need to be added to this, to either maintain it within target bands, or restore it to within target bands.

In this way, scheduling is effectively an inventory management process, which is both a key part of mine scheduling and also one that is underutilised. Inventory management will be discussed in further detail in a later blog to come.

Kick-starting my Career

When starting my career as a mining engineer, there were many things I wanted to gain in the first few years; experience, experience and experience! The on-site consulting world has offered me this in spades! Throughout university we were often told of the benefits and diversity of skills we would gain while undergoing a graduate program with a well-established mining company, so when I was faced with the decision of continuing my job as a Graduate Consultant or applying for the much sort after graduate rotation positions I felt as though they had it all. I loved my job and the culture of the company I worked for, Echelon, so I threw caution to the wind and didn’t apply for any of the roles I had been prepping for over the previous four years. It turned out to be one of the best decisions I’ve ever made! Especially when they took us to Aria for Christmas lunch!

Over the last two years with Echelon (who became Xstract) I have had the opportunity to work on many different mine sites, learning best practices across the industry and seeing how different people and teams tackle the same issues every mine faces. It’s been great to be able to apply my skills to different situations, introduce new ideas to a technical services team and also rack up my frequent flyer points. Across these different sites and the Brisbane office I have worked in various roles; short term design, medium term design, life of mine scheduling, and pre-feasibility and feasibility studies. To have had exposure to all aspects of the mining cycle has been great, work is never boring and I’m constantly learning new things and looking at mining projects from different perspectives. It has also been a good way to learn where my passions lie and decide what career path I want to take in the future.

From day one I was given real responsibilities and accountabilities and I quickly learnt superior time management skills, making sure that I am always producing quality work in a timely manner for clients. Working with a close-knit team of consultants means my colleagues are always eager to help me learn new skills and various software packages, sharing their combined experiences with me on a daily basis. The faster I mastered a new skill, the sooner I could contribute to client jobs or take ownership of onsite roles.

One of the best parts of my job is the unmatched opportunity I have to network. Building up relationships with accomplished engineers across the coal industry and making friends in new places, predominately small mining towns, will no doubt benefit me time and time again.

I have found a job where I am part of a family, I am expected to “hit the ground running” and own each job I am tasked with, and I love it!


Caitlin McCarthy

(1) The Broken Stocks Saga

Many years ago in an iron ore mine I was the Grade Control Superintendent, leading a team charged with producing weekly stockpiles of lump and fines ore. This position was located in Mine Production Dept rather than Mine Planning Dept. Between the two ore stockpiles, there were a total of 8 target qualities with very tight target bands - so quality was "king".

Mine Planning Department were responsible for short term schedules of all mining equipment over a 3 month time frame, the primary schedule driver being that of the excavators mining "specification product" on a weekly basis.

Now broken stocks (material already blasted) are extremely critical in weekly ore stockpile construction, as they’re pretty much all there is available to mine from within that time frame. We came into a situation where we had very high phosphorus in our broken stocks, which made it near impossible to build stockpiles to our quality targets.

Our problem was that Mine Planning Dept produced plans that effectively continued to add target quality material at one end, while we attempted to take target quality material off the other end. Consequently the high phos broken stocks weren't being remedied. So for a sustained period of nearly 2 months, the broken stocks continued at high phos levels and during this entire period we really struggled to produce "on spec" weekly stockpiles. And yes this was very much a saga for me with the heat we drew from sending out "off spec" product!!

This situation was a catalyst for many learnings for me personally and these will be discussed in my following posts.