Milling

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Anyone who has had the experience of being here at the distillery when we are milling will have seen a sight only familiar to persons of a certain age. It is very unusual to see belt driven machinery anywhere these days but at Springbank we take great pride in the fact things haven’t changed much here in the last half century. A large single electric motor drives the main shaft which in turn drives a number of conveyors, elevators, a dust extractor, a drum screen and the mill. It is very rewarding to see the faces of people who see the mill in operation as they all, without exception, take delight in seeing belt driven machinery and will tell you it is an amazing experience. The noise, the different sounds, the smells and the sight of the mill in operation all add to the uniqueness of a visit to Springbank.

Why do we mill the malted barley? This is a question I am often asked and the simple answer is to allow the water to penetrate into the malted barley and convert the starches and protein into soluble products. The milling process allows us to prepare a grist of a consistency that allows fast wort run off and good extraction efficiency.

It is important to get the milling process right as it plays a major part in how efficiently the distillery produces alcohol. Malt is transferred from the selected malt bin through a conveyor, into an elevator, down a chute which has a large magnet for catching bits of metal and into a drum screen which removes any foreign objects and small corns. The cleaned malt passes down into the weighing machine and then into the malt mill, each coup of the weigher is 40 Kg. The mill is set to grind the malt into grist which contains 20% husk, 70% grits and 10% flour, this is the ideal consistency for our mash tun to allow clear wort drainage and good extraction. The grist as it is now known is transferred from the mill along a conveyor into an elevator, across a conveyor and finally into the grist bin where it will stay until needed.

The consistency of the grist is constantly monitored throughout the grind to ensure the mill is doing its job effectively. The operator takes a sample of approximately 120 grammes from the bottom of the mill and places it into a sieve box. The box has sieve screens with holes of different diameters the top sieve being larger than the bottom sieve. The lid is secured and the sieve box is shaken a number of times before the different fractions are weighed. Each fraction is weighed independently and a note of the weight taken. The husk, grits and flour weights are combined to give a total weight. Each fraction is then worked out as a percentage of the total weight.

As usual, anyone who would like a deeper understanding of the milling process please feel free to drop us an e-mail.

All the best

Stuart Robertson
Distillery Manager