A question has been asked as to why Roach's Mill was so high. For those technically minded, below is a description of how Roach's Mill worked in 1885 after additions were made. The description is from Pictorial Australian Tuesday 1 September 1885, page 143 and was found on TROVE.
In 1885 it is boasted that Burra is "the largest corporate town in the colony, excepting the city and suburbs." The writer also states " It is to be regretted that the building was not two or three feet larger either way. This would have given the workmen easier and safer access to the machinery; at the same time it is apparent that the room has been utilised to the best possible advantage." The whole process would probably be seen as a occupational health and safety nightmare in comparison with today's standards but in 1885 was "state of the art".
One of the chief industries of the Burra district is that of milling, and no wonder either, for, though once considered little short of a barren desert, it is now one of the great farming centres of the colony. Of late years, since Victoria has come into the field as a competitor in the production and exporting of grain, S.A. millers have been obliged to export their surplus more to the United Kingdom, and are very much chagrined to find that though the colony has a high reputation for its superior wheat, their flour only takes a third-rate position in the home markets. The cause has been assigned to the carelessness of the millers in exporting stuff from inferior grain, but some blame the primitive milling apparatus used, and this latter belief is the more probable, for the primest brand offered in the London market was the " Hungarian."
This, it was known, was produced by a new system— the roller — and when the fact became recognised, several South Australian millers determined to have the latest plant. Amongst these were Messrs. Roach Brothers, of the Burra Mill.
On Thursday, January 22, a number of gentlemen from Adelaide interested in the grain trade, and a representative gathering of local townsmen, assembled to see the starting of the roller-mill in the township, the hope being freely expressed that this would restore to that town some of its departed eminence.
At considerable expense the members of the firm had completely replaced the old "stone process" by "the roller." The Mayor of the Burra (Mr. J. Dunstan, J. P.) started the engine, and then the company dispersed to examine the new plant. They were informed that, in order to put themselves in a position to compete with the flour of the world, the proprietors of the mill had determined to try the most approved modern methods of milling.
For this purpose they communicated with an Austrian milling expert and engineer instructed him to submit a sketch of a process which would give the best possible results from our very superior South Australian-grown wheat, and ensure their turning out a quality of flour equal to anything manufactured in other countries. This sketch being approved, the mill was forthwith stripped of every particle of machinery, leaving only the floors and bare walls, and working plans prepared, making the best use of the room at disposal.
It was found that the alterations could not be thorough without the addition of another story to the building, and Messrs. Roach Brothers decided to make this necessary addition. Plans were submitted in due course and approved.
Messrs. Harrold Brothers, the South Australian agents for Ganz & Co., cabled to Austria for a complete set of their celebrated roller-mills, as well as a large quantity of German and English dressing and purifying machinery of highest repute.
Messrs. J. Martin & Co., of Gawler, were the successful tenderers for the iron work and a new 42-h.p. horizontal engine.
The work of demolition was immediately commenced, and the alterations were just six months in hand. The mill is favourably situated in an isolated bend of the Burra Creek, right in the centre of the town, which boasts of being the largest corporate town in the colony, excepting the city and suburbs. The building of the mill proper is 40 feet by 28 feet, and five stories high. The height is 54 feet to the gable point, and with store, wheat-sheds, and adjoining outbuildings forms an imposing structure.
On entering the main building the impression conveyed is that the mill is on a very different principle from the old stone process. Instead of the long row of gear-wheels and pinions with which the initiated are familiar, a long shaft running nearly the full length of the mill is visible. On this is a forest of large pulleys, with driving belts leading through the floor above. The speed of this shaft is increased from 50 revolutions per minute (the speed of the engine) to 150, by a large cog-wheel working into a small pinion wheel of the same nature. On the second floor are, compactly arranged on either side of the centre of the building, two rows of the roller-mills, consisting of five of Messrs. Ganz & Co.'s grooved cast steel, three smoothed chilled iron (each containing two pairs of rollers), and two of Hegmann's patent porcelain mills.
Here, also, are fifteen sets of elevator spouts running vertically between the floors, most of them being the full height of the mill. On the floor above is a network of galvanized-iron feed-pipes, conveying the various products hither and thither, and a host of wheels and belts, besides a few bins for cleaned flour, wheat, &c.
Another of Hegmann's porcelain mills for finishing purposes is also on this floor, as well as a large Haggenmächer purifier for cleaning coarse sharps, the best machine of its kind made. It is of elaborate construction, and, with its thirty, or more small glass shutters, somewhat resembles a child's peep-show.
Ascending to the fourth floor a maze of belts, wheels dressing machines, &c., are witnessed, with gangways in every direction On this floor are seven dressing reels of varied construction, wheat-screens, a large dust or stiveroom, which takes the first blast from the purifier fans, four machines known as Luther's vertical purifiers, standing 8 feet high, with cylindrical bodies, through which the fine sharps are passed and cleansed from all impurities, after first being graded or sorted by a silk reel on the floor above.
On the top floor are eight more dressing machines, detachers, another stiveroom, and a network of wheels.
The appointments throughout are excellent, and reflect credit on the engineer, under whose supervision the work has been carried out. It is to be regretted that the building was not two or three feet larger either way. This would have given the workmen easier and safer access to the machinery ; at the same time it is apparent that the room has been utilised to the best possible advantage.
The process of manufacture, followed out in detail, is highly instructive and interesting. In order to avoid, as far as possible, traffic through the mill, the proprietors have constructed a large receiver, or bin, into which loose wheat to the extent of 13,000 bushels may be tipped, and from here it is taken by means of a screw 53 feet long into the mill to be operated upon. It first passes through the cleansing rooms, where the grain is thoroughly screened and cleansed on the most approved modern principles, by scourers, brush machines, and fans.
The cleaned wheat is then passed to a double set of Ganz steel roller-mills, of 250 grooves coarse. Here the grain is merely split in two and returned to elevators, which take it to a wire scalping reel on the fourth floor. As no amount of cleansing with the grain in its original state can remove the dirt, the necessity of splitting is apparent, but this process loosens the dirt, which is taken out by the wire scalper. The small particles of sharps and flour which must necessarily come away with the dirt, are then put aside as offal.
The tailings from the scalper are next passed on to No. 2 roller-mill of 350 grooves, and further reduced ; then through a wire scalper, which takes out and grades three sizes of sharps.
The term sharps is applied to the wheat when it is broken by the roller without being pulverised, and as the different gauge of rollers is applied to the wheat in turn, the whole of the shell is taken away, and flour is produced in a state of cleanliness never attainable with the old stone mills.
The three sizes of sharps are each treated in a different manner. The finest is further dressed and graded on a silk reel. The medium passes on the Haggeämacher patent purifier, where it is further graded or sorted, and through the agency of powerful blasts of air all light matter and bran speck are drawn off into a large exhaust room, while the heavier particles containing flour drop through the current of air . The coarsest sharps come back to another finely grooved roller (600 grooves), and are further reduced, and then purified. This same process is twice repeated on the roughs that remain, on two sets of double rollers of 450 anc 500 grooves respectively, with the same routine of dressing, the finer sharps being first graded, and then purified on the Luther vertical machine. This finishes the bran.
But the sharps have yet to be reduced to flour. This is gradually effected on three sets of smooth-chilled iron and three porcelain roller-mills in rotation, the constant dressings on silks of various kinds being necessary after each set of rollers.
The flour from the different silks falls into a screw underneath the third floor, running nearly the full length of the mill, and is then taken by elevators to the fifth floor, where it is again put through a long silk reel, which in addition to thoroughly "mixing the flour, and making it of an even quality, acts both as a safeguard and tell-tale, for should any coarse particles by some mishap get into the flour, this silk extracts them, and at the same time their presence at the tail notifies something wrong in one or other of the many silks.
From here the flour falls into the pastry and is bagged off. It will thus be seen that the process includes nine distinct and separate treatments on rollers, and no less than nineteen dressings on silks, wire reels, and purifiers. It is therefore rightly named a "gradual reduction process."
Each bushel of wheat treated will travel over 1,800 feet up and down and across the building in straight lines, while to puzzle out the actual distance, reckoning the revolutions of the silks, would be an arithmetical problem. The mill has worked day and night almost unceasingly since first starting, and Messrs. Roach Bros, have a large and increasing demand for their flour at prices exceeding that made with mill stones by as much as 30s per ton. They are determined to keep in the van by adding each new development in milling machinery as it comes into notice.
At present they are arranging for the lighting of the whole premises by electricity.