On the 25th July 2012, Martin Poulter and Adrian Fewings, the founding directors who started the Derbyshire Specialist Aggregates in 1984, got their chance to visit Salt Union Rock Salt Mine at Winsford Cheshire. They toured the mine and production facilities of the UK's biggest Rock Salt mine.
Here is an account of their day:
"It was a warm sunny morning in what was one of the hottest weeks we had had for some time and we arrived at the site to see a great pile of salt, a few small buildings and a couple of unusual sheds. It wasn't quite the operation we were expecting. However, we were later to learn that the whole operation is underground and the final finished product is elevated to the surface stockpiles ready for sale.
We got kitted out with helmets, glasses, overalls, lights, emergency breathing apparatus and individual personal swipe tags, then proceeded to a small cage where we entered to take our trip below. The descent was quite quick and 14 degree temperature much cooler than the surface as we walked out into some pretty impressive passages and tunnels.The Cheshire rock salt is pink in colour due to a material called marl. It represents a small percentage of the salt but gives it a distinct colour. The marl was a material blown in when the vast salt water lakes were drying out. The salt layers built up over many years of flooding and drying cycles to form rock salt beds which are now worked today.
The area being worked is vast. One hundred and fourty miles of tunnels and galleries up to twenty metres high under the Cheshire country side measuring about six square kilometres with three distinct levels of available salt. Our hosts were driving us around in a mini bus with lights all around so you can see the workings stretching out either side as they drove along the main access routes. We passed some very impressive machinery everything we expected to see above ground was all down there: shovels, excavators, crushers, screens, conveyors offices workshops and further stockpiles of mined rock salt ready for processing. Being underground the process has no weather or seasonal issues and can work 24/7 all year round if needed with the extraction of the rock salt being done principally with two joy mining machines and some drilling and blasting as well. The joy mining machines cut into the mineral with large revolving cutting heads producing a crushed product out of the rear onto a walking conveyor unit following as the joy machine works its way forward into the seam. The semi crushed rock salt is then conveyed away to the crushing area near the lift shaft ready for processing and elevating to the surface stockpiles for sale.
The underground area is massive, but they have only scratched the surface of what is down there and the process of leaving large pillars as support means there is no movement or safety issues, the elevating process to the surface is done in eight tonne skips with about five hundred tonnes per hour at full capacity. The salt mines annual output is over one million tonnes per year but that is dependent on the weather.
The main issue is getting salt to those who need it in bad weather. We all want the salt when it snows, and we can't get to the mine or out from our packing sites. Everybody else is trying to do the same so the mine can't cope with the traffic levels and must restrict lorry movements to a manageable level.
The main problem is that we don't know what the winter will bring. They could be hit with orders of half the amount or double with councils and roads taking priority. For businesses needing packed salt, volumes, logistics and supply restrictions can be critical so careful planning is essential. You can store salt in bags indoors indefinitely and one thing is for sure - you will need it sometime. If you have room keep some safe.
I have been in some mines before but this was impressive. This has developed to safeguard our country's roads, highways and car parks without which we would have to import at greatly increased costs to businesses and councils alike."