OREPUKI SHALE WORKS.

Otago Witness, Issue 2410, 10 May 1900, Page 37

OREPUKI SHALE WORKS.

One of the most interesing visits made by i the Minuter of Mines and party during the ' recent tour was to the New Zealand Coal and Oil Company's works at Orepuki, where shale is to be treated on au extensive scale asd its products placed tipon the market. Mr W. P. Watson, general manager for the company, was in the vicinity at the time, and kindly made provision for conveying the party out to the works, a distance of a little under two miles from the township, and at the appointed time the party proceeded over the company's line of rail. A very short time sufficed to cover the \ distance, and on their arrival aj cordial recep- ] tion wp* experienced at the hands of Mr Robert Dunlop, manager for the company and an expert in shale-oil manufacture, and Mr Straw, ' mine manager. A visit was first made to tinlaboratory, where samples of the various grades of oil extracted from the shale by chemical process, and scientific instruments (an explanation of the use of which proved most interesting), were shown. Specimens' of "tlie wax were also seen. The party, under the guidance of i Mr Dunlop, then visited the granite quarry situated in the immediate vicinity of the works, j Mr Eunlop, besides having a complete grasp of the particular work upon which he is engaged and other matters of a kindred nature, is an amateur photographer of considerable skill, and was not satisfied to leave the shade of the bush until he had " caught " a picture of his visitors. The party were then taken over the works proper, which are still a long way from completion, though their erection has been busily pushed forward for some considerable time. It is assumed that it will take from six to ten months before they are finished. The outlay in capital has been very large indeed, but once in good going order the industry is regarded as .certain to give a very handsome return on the investment, and an assurance to that effect is given by those most capable of judging. A good seam of coal underlies the shale in the mine, and will prove of utility. Some of the party, who had come prepared for . &uch an emergency, penetrated the shaft to some considerable distance, and had an opportunity of making a close inspection of the seam j of shale, and while they were thus engaged the remainder paid a visit to where brick-making was carried on, and the proposed site for the 1 workmen's houses was pointed out. At Mr Dunlop's invitation the party then took a rest at his private house, which practically overlooks the works, snd were there much interested iv an inspection of his collection of antiquities and curios, iv the .gathering of which Mr Dunlop evidently takes a keen pleasure. Many of these are exceedingly valuable on account of , their great age and rarity. For the short time | spent in his company, Mr Dunlop proved a I most interesting companion, and Jiis evidently inexhaustible stock of valuable information on scientific subjects went very far towards proving I the tiuth of a casual remark made by himself ,' that he had never wasted a moment all his life. He nlio mentioned incidentally- that the works would probably be the means of increasing the population in the locality to the extent of 700 or 800 people. Nothing could exceed his kindness, nor that of Mr Watsou and Mr Straw, who all certainly did all in their power to make , the visit of inspection the pleasant one it urc- \ doubtedly ws s. i The following particulars concerning the , treatment of shale and of the works were very | kindly supplied by Mr Dunlop: — The oil industry in xJritain extends away back into the seventeenth' century, as in the ! year 1694 a patent was granted for the produc- | tion of pitch, tar, and oyle (oil) out of a kind of ! stone. "Very little progress was made, how- ' ever, until the year 1781, in which year the ' Earl of Dundonald (of whom the Dundonald of Boer fame is a lineal descendant) discovered how to make oil and tar from a kind of coal, i He corriod on his destructive distillation m ' ovens or retorts very similar to those in use at the present day. Early in the nineteenth | century many valuable discoveries were made, &uch as paraffin from wood-tar by Reichenback, i in bituminous shale by Laurent, and in coal I tar by Dumas ; but those products were simply . scientific curiosities, and it was reserved for , Dr James Young, of Renfrewshire, to make j them marketable products. In 1847, when, manager of a chemical works at Liverpool, his attention was directed by Dr Lyon Playfair ] to a small stream of oil flowing from, the top of a coal working at Alfrelon, in Deibyshire, and from this oil he succeeded in extracting marketable products — such as burning oil, wax, j and lubricating oils. When the supply of this | oil got exhausted he naturally looked for other i sources, and, like all true scientific men, he ! imitated what he thought was Nature's . method — the action of a gentle heat on coal or sliale. While he was still experimenting, a highly bituminous coal was ~ discovered m Scotland, known as the Boghead coal (afterwards as Torbamhill mineral), which he found | to contain from 120 to 130 gallons of oil per j ton. It was to woik this shale that he took out his patent, No. 13292, and it was this shale that the famous lawsuit was about. The discovery of enormous quantities of petroleum in America so much reduced the market value of the products in Scotland that the history of the oil trade for the la3t 20 years has been one great struggle against excessive competition from abroad. No sooner was an improvement made and the cost reduced to meet a decline in the selling market, than another decline had to be (faced, and it ia quite safe to say that no other industry in Scotland has fought such a noble battle to save it from extinction. The 1 cost of refining a gallon of crude oil has been 1 reduced from 2.2 d to 0.7 d, and this includes the refining of the wax; and the yield of sulphate of ammonia has been raised from a few pounds up to4olb tc 601b per ton. Petroleum ia found in different geological periods of time. In the United States and Carada it is generally found stored up in the porous sandstones or limestones of the Devonian or Silurian period. In Efi3?»t, India, and Konmania it iff found in

the Tertiary strata; at Baku it is founds !m the later Tertiary and Cretaceous and Jurassic ages; in Galicia it is found in the lower Eocene and upper cracaceous rocks; Hanover in the gault beds of the Jurassic, and also hi the Triassic age. In New Zealand I have examined half a dozen shales, and they all appear to belong to the Tertiary or Jurassic age. Shale is now well known to be of either vegetable or auirnal origin, and sometimes of both. In Scotland some of the shales are almost entirely made up of a small microscopic organism called entomostraca. Shale oils are generally composed of carbon afld hydrogen, with nitrogen, sulphur, and oxygen in small quantities. Most of the nitrogen which the shale contains is driven off as ammonia, and some as organic bases. The oil when refined is a comparatively pure hydro-carbon, and the blower and more gentle the shale is cooked the better the oil is. The element carbon is only able to take up or combine chemically with four atoms of hydrogen to one of carbon, which forms a type molecule of the parafnn series, and is sometimes called saturated hydro-carbon, because the number of atoms of hydrogen exist in the fullest pioportion in which those two elements can combine. If the retort is over-heated the molecule lose? hydrogen and is formed into the olefin series, two atoms of carbon to eight of hydrogen, and if still more heat is applied it goes into tlie benzole series, tliree of carbon to eight of hydrogen, hence the use of steam to prevent the paraffin molecule from losing its hydro%en. A better method for preserving the paraffin molecule, o£ of building up the lower series to the higher, is still to be discovered, and would be one of the best discoveries in the history of the oil trade.

The plat>t which is being laid down in Orepuki is of the latest and mcsl improved type, the result of 50 years' research by many workers in Scotland. The retorts are the best known lor this particular shale, and while they will preserve the oil it is expected they will also give a big yield of sulphate of ammonia. The* shale field hao been tested over a large area, and found to be nearly uniform in thickness, and giving a quantity of oil over the average shale in Scotland. The mine has been put down over 900 ft at a declivity of 1 in 4, and is in the centre of a basin, so that the shale and water will go to the bottom without any great expenditure of power. When tlie shale comes out of the mine it is put into a breaking machine, and when broken is raised by elevators, and put into hoppers on the top of the retorts. The shale in the retort is kept in continuous motion by machinery, and when exhausted liois out at the bottom. By means of a fan the oily vapour is drawn through a series of condensers, where the gases are cooled, and the liquid portions (oil and water) run into a large receiving tank. The gas passes on through two large towers, where it is first scrubbed with water, which robs it of its ammonia gas, and then with oil,' which lobs it of its spirit. The gas then goes on to the retorts, where it is used for firing Sulphate of ammonia is extracted from the water which comes over along with the crude oil, and the crude oil is pumped up into a large tank, separated from any water which it may contain, and then run into the still. The still is then heated up, and the oil vapour passes over, and again condensed and run into a receiver. During the distillation steam is passed throtigh the still to bring over the oil at a lower temperature and preserve the paraffin molecule. After the distillation is finished there is a coke left in the still, which is used for making moulders' blacking, and for burning in parlour grates, as it gives a good heat I and practically no ash. The oil in the receiver is next treated with sulphuric acid and soda hydrate and again distilled, and this time ! cut into light and heavy portions. The light [ ijortion- is again distilled, and ogam treated, | and is finished burning oil. The hea"y portion | goes-to the paraffin shed, where it is frozen, 1 and the paraffin wax extracted. The oily por- , tion is again treated, and distilled and cut up into the different kinds of- lubricating oils. , These lubricating oils aie again frozen, and more wax extracted ; they are again treated, _ and are ready for the market. The paraffin* j'wax is again put into a sweating house, where j the temperature is gradually raised, and any ' oil which it contains comes away first, bringing a lot of impurities with it. then the lower j melting point wax, and lastly the high melting | point wax. which all run into different rej ceivers. This process has generally to be «one 1 thiough twice before it is ready for the final touch, which is to pass it through animal j charcoal, which decolourises it. It is then ■ run into cakes, and is ready for the market. ■ The high melting point wax is used for candle making, and the lower melting points are used for match making and many other purposes, i When dissolved iv spirit low melting point paraffin makes o splendid damp repeller, and , when put on a house in summer is said to last I a long time. A coating of wax is said !to preserve fiuit and butchei meat. Tt is I used by brewers for coating the inside of beer barrels, and by weavers in the manufacture of yarn and cloth. It is also used for making | cork impsrvious to air, and as a nonconductor j by electricians. One of the bad uses it is i put to is to adulterate sweetmeats, which pracj tice wos severely criticised in the Science Sifcj inps some time aao. Paraffin wax, when well ! refined, is a wax-like white or colourless crys- , talline substance, and is not so£ed on by either j acids or alkalies, and is one of the most stable ' substances known. The spirit extracted from | the gas is called naphtha, ar.d should have a sp. ] gr. of 730 to 760, and is used for extracting fats, j oils, and similar bodies, and in the preparation ! of paint and varnishps. , The acid and soda | tars, when neutralised, are used for making I coal briquettes, and foi asphalting purposes, j "Wlieii tilir- elections are completed and the i work in full going order 2000 pa lions of crude oil per day will be put through, and this output can be doubled at a comparatively small cost, as the bulk of the plant for this increase is being erected now in the original works.