THE SHALE WORKS AT OREPUKI.

Otago Daily Times, Issue 12036, 7 May 1901, Page 6

THE SHALE WORKS AT OREPUKI.

HOW AX IMPORTANT INDUSTRY IS TO BE CARRIED OX. Tho Xcw Zealand Coal and Oil Company's works at Orcpuki, bettor, perhaps, known as the Orepuki Shale Works, represent an undertaking of great magnitude and colonial importance, and we feel Bure that very few people in the -Middle Island, and certainly almost, none.in the North Island, ran have the slighlcft conception »f the expenditure this enterprising company lias undertaken (luring tho la 4 two yoare.aml a-lialf. under the very capable management of Mr Dunlop, uf Airdri*, Scotland. The works am situated at. Orepuki, which is about 44 miles west of luveroargill and about two miles out of the township at the end of a branch line of railway owned by the company, and to attempt a description of them in a way that would convey anything like an adequate idea of TPIKIR EXTENT AND NATURE would be almost- ufoIos?, unless to persons wlio have bad previous experiento on the subject. Over 1.500,000 bricks have been absorbed in the'erection of the various buildings required tn hou.'p iiie complicated and expensive machinery necosfary to produce -a marketable article from the shale—which consists of burning and lubricating oils, paraffin wax, naphtha, euliihatc of ammonia, and other products too numerous to mention—and the ?.O retorts, which ro up to a height of 70ft, in a solid massive structure. The mine i» opened up by a dip drivo 900 ft in one to fonr, and the shale, when brought to bank, is thrown into the jawn of a powerful shalc-broater, and immediately crushed anil raised to the top of the lofty retort? with suitable machinery. The rctprte are 20 in number, and are canable of putting through 60 tons of material per day. Tho shale while in tho retorts is kept constantly revolving by very ingenious machinery, and when the oil ami gas are completely extracted the spent shale falls into tho trucks below and is Bent to the waste heap. ' Tho mil when it comes from the retorts pawes through the condensers and runs out as oil and water— the oil in one lank, the wator in another. The gas ffoxn tho condensers having been cooled u passed through two large towers, where it undergoes an interesting and ■

SOMEWHAT 'CURIOUS PROCESS. In the first tower it is "scrubbed" with water; that is, a large steam pump constantly payees water through it, and the result of this operation is that ammonia is , extracted from it. This ammonia, is subsequently treated with sulphuric aeid and made into sulphate of ammonia, and sold Jβ manure. In the second lower the gas is next "scrubbed" with oil in the same manner as it is scrubbed with water. The steam pump continually passes oil througiv it, and the result of /his" operation is that naphtha i« extracted. Naphthizin; is generally known, boiii? ueod for driving launches, in tho preparation of paints and varnish, and in oilier directions. The gas having now been robbed of this spirit and of tho ammonia goes back into the retorts, where it is utilised to keep tho retorts at a whito heat, while- fresh shale is pas'iug through, it will thus be Foen that the shale is treated on an automatic principle. Gas is extracted from it, and then passed infy tho retorls and kept burning while fresh shale is being operated on. The work of firing the retorts with |ian i*, as may well be imagined, an operation requiring delicate and cautious bundling. Tho amount of air that is admitted to the retorls must be adjusted with scientific nicety, for if too much air is iHlmi'ted a difastrou's explosion might eiinic. _ The appearance of Ihe retort? at night is remarkably fliio. if no! awesome. Ihe huge brick retorts loom high'into the air, like the side of an immense structure, and from immcroiu f ma!l holes .

THE (U,EAM OF A FIERCE FIRE streams out into the air. A glance through one of these holes, however, reveals nothing in tho shape of holes. When the gas passes through the retorts complete combustion takes place, and the result is a white, glowing, palpitatiiijf firr— a Tiro without flames impalpable and silent—the sight of which is a veritable glimpse of the infernal rugions. Wβ have now iloun with thn retorts, and pass down to the huge 8000 gallon tanks which contain tho water and oil that havn run off from thn condensers. The oil, thick, green-coloured, and hot, u, we find, running slowly into one coni'iartmnnt of the tank, the water into another. Although a certain amount of ammonia wa« extracted from tho gas in one of the towers previously referred to. the bulk of the -ammonia is obtained from the water just mentioned. The water undergoes a treatment which extracts from it the ammonia and a certain percentage of oil that may have escaped with it, and is then run away. The oil in the other compartment- of the tankrepresents, of course, the chief product of the shale. Il has now to be subjected to processes which will cause it to

YIELD WAX AXD TAR, and which will convert it into oil for household use and for lubricating purposes. Tho first thing done to achieve this is that the oil is pumped into a still, or stills, for they are 10 in number. They are capable of distilling; 2000 gallons in 24 . hours. After the distillation a coke is left in rlic still which is used for making moulders' blacking and for burning in parlour fires. It leaves little ash and gives "a good beat. As the oil comes out of the still in. the form of a vapour it must be again condensed. Accordingly onco more it passes through condensers. The vapours .'are reduced to tho liquid oil, and the oil is run into receivers. These receivers, 10 in number, are each capablo of holding 2000 gallons. The next 'step to bo taken is to get tar out of tho oil, and accordingly *il is blown through pipos from thn receivers into large iron tanks, where it is treated with sulphuric acid. This causes certain bodies in tho oil to becomo dissolved, and tho combination of tIiCEO bodies and the sulphuric acid creates what is called an acid tar. This'tar in appearance is exactly similar to that used for' asphalting, etc., but before it can be. sold for that purpose it has to be what is termed neutralised. Tav is daily ranking higher as an article of commercial value. Many industries urn at proiont in existence in Europe and elsewhere where tho products of tar are being.utilised and manufactured into various marketable products. Tho oil having been divested of the tar is once more, passed through stills. When the distillation is over the

FIRST OIL I'RODUCKD is light and thin, but subsequently tho oil gets dome. When tho stream becomes of a certain speeifio gravity, it is switched off into another receiver, so that the oil is now divided into a light oil and a heavy oil. The light oil is further distilled and chemically treated till it eventually becomes tho burning oil now in domestic use. Tho heavy oil before it can be converted into lubricating oil has, however, to go through inoro extended processes. It contains paraffin wax, and tho next phase of those interesting proceedings is to extract tho wax from it. Tho method by which this isdone is a little peculiar, inasmuch as tho oil lias to 1)0 frozen. Tho oil is first conducted to what is called the paraffin sheds, and tho frooziiiK process is brought about through its boing put through what is called a Henderson's cooler, where tho temperature is reduced by cold brine. In it.s cool rtate the oil becomes semi ;;olid, and it is then pumped into filter-presses. Theso presses, built 'of steel, squcozo tho oil out of the partially-solid fluid; tho presses aro then opened, and tlio wax drops , out into a, tank at tho bottom. Onco inoro, then, the oil is chomically treated and distilled, and when it runs out of tho still it is divided into a light and heavy oil as More. Tho wax, hmrevor, i* not yot wholly extracted, so the oily fluid is again frozen and squeezed through tho pres?os. and tlio oil which now comes away, after being finally treated, i.i at length ready for market as lubricating oil. Tho wax which comes out of the presses has also to undergo treatment before it becomes

TIIK TURK WHITE SUBSTANCE known to commerce. It is first put 'into a refinery or sweating house, whero tho ternporaturo is gradually raised. Any oil it may contain first comes away, and with it tlio impurities in tho wax also run away. Tho wax itself is divided into two kinds— firet. the lower-melting-point wax, and, secondly, tho liijrh-mriting-noint wax. Aβ its name would imply, the wax. which first comos away in tho fweating-bouse h the lower-melting-point wax. Tho bigh-molting-noint wax is that which resists tho he.it longest. Tho wax as a nJe has to bo nut through tlio process in tho sweating twice bnfor.' it is ready for -fhe finishing .touch, which, as Mr Diinlnp explains in tho articln abovo referred to. is tn pass it through animal charcoal, which decolourises it. It is then run into cakes, and is ready for tlio market.