43
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NORTH YORKSHIRE POTASHA
66
sid on Boulem, seufimo, bw, n; tail bolamites nest zen 199. In 1938-39 an exploratory borehole for oil was sunk by the D'Arcy Exploration coe Ed. dt Aislaby, near Whitby.............. Aadetalled statement of the information revealed by the borehole was announced in a paper by Dr. G. M. Lees and Mr. A. H. Taitt (of the D'Arcy Exploration Co.) read to the Geological Society of London on 6th December, 1944, and published in the Quarterly Journal of that Society in February, 1946. It may be summarised as follows: (i) e coroni (1) o medo read, ad vito, dofdw easts Jaugel ulle volqxs It JA of wod (vi) bu elley inbor & gb (th (i) A salt bed was recorded at a depth of 3,655-3,680 ft. containing not more than 1 per cent. potassium chloride (KC1), with a thin band of 3.2 per cent KC1 at 3,800 ft.
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(ii) A second salt bed from 3,920-4,193 ft. containing a thin bed of
sylvinite" with up to 34 per cent. KC1. Further records of KC1 were obtained immediately below this, but owing to incomplete core recovery, the exact thickness and quantity are unknown.
3
(iii) A third salt bed from 4,312-4,775 ft. containing a solid bed
polyhalite with 15.6 per cent. potash (KO) about 45 ft. thick.
URUTERA Zi goißimoin (iv) Natural gas, about 95 per cent methane, under a pressure of 1,650 lbs. per sq. in. was struck at 4,212 ft. A short test gave gas production at the rate of 2.5 million cu. ft. per day.
(v) Near the base of the borehole at a depth of 4,870 ft. water was encountered the analysis of which showed 11,370, 1,036, and 19,028 parts per hundred thousand sodium (Na), potassium (K) and chlorine (C1) respectively. This represents almost a saturated solution of brine, containing, in addition, some KC1 in solution.
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Owing to the collapse of the borehole, particularly at the salt horizons, the existing borehole could not be used for any further exploration or for longer pumping tests on the supply of natural gas and brine available. .griamoriq
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200. Geological evidence from the borehole and the surrounding district suggests that salt beds of the type recorded are likely to occupy a consider- able area extending mainly eastwards and not to be isolated or fortuitous occurrences. Such deposits were produced by the evaporation in Permian times of a sea, called the Zechstein Sea, long known to geologists as having once extended across North Germany to East Britain. Important deposits of similar salts which accumulated in the same sea have been worked in Ger- many on a large scale for many years. It will be noted that the existence of two different potash salts has been recorded; sylvinite » containing KC1, and polyhalite containing potassium sulphate; of the two the former is by far the more important as a raw material for manufacturing fertilisers. Unfortunately, for technical reasons and because the boring was for oil, the recovery of the core from the borehole was incomplete in the salt horizons where KC1 was recorded.“
mori conervari que le ha inshness on bin 201. The attention of Imperial Chemical Industries Ltd. was drawn by the D'Arcy Company to the salt deposits, which were not then known to contain potash salts, and they were invited to examine the borehole cores. The salts were found to consist chiefly of common salt (sodium chloride), anhydrite (calcium sulphate), "sylvinite" (mixed potassium and sodium chloride). Polyhalite (a hydrous sulphate of calcium, magnesium and potassium) was afterwards regognised ofobe present by Professorage 69: ofnsides and Professor C. E. Tilley.
44
2o 202- No action was taken in regard to further exploration until 1948. Prior to that time the Imperial Chemical Industries Ptd, who were already working anhydrite and salt further north in the Teeside area, did not con- sider the information then available justified further exploration from the commercial standpoint. However, in 1943 they drew the attention of the Ministry of Supply to the occurrence in view of a possible decision by that Ministry to undertake exploration as a wartime emergency measure. This information was brought to the attention of the Non-Ferrous Metallic Ores Committee (Chairman Sir William Larke, K.BE), which reported that the discovery was potentially important and recommended that if home-produced potash was required, immediate steps should be taken to ascertain the extent and thickness of the deposits by means of further exploratory boreholes. This report also recommended that the mineral rights covering the potash occurrences should be nationalised. WSC to digs & of one need
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203. It was eventually decided not to proceed at that time! since it appeared that even should further boring give favourable results, the opening up of a mine at that depth to develop the deposits would be a long-term undertaking and costly in money and manpower. Other ways of working the occurrences, i.e. by pumping the brine at the base of the borehole, were apparently not considered.
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204. In September, 1946, immediately after our appointment, we thought the facts should be re-examined without delay in view of the potential importance of the discovery. IC.I. kindly supplied us with further reports and their attention was naturally centred on the possible value of the sub- stantial deposit of polyhalite (para. 199, iii). Their opinion at that time was that, while more information about the deposits was essential, and because further boreholes would be costly, we should arrange some preliminary re- search work on the value of polyhalite as a fertiliser and investigate the cost and practicability of mining it at about 4,500 ft. The existence of the methane gas under pressure immediately above the polyhalite would have. added to the mining difficulties. From the commercial point of view, Imperial Chemical Industries doubted whether on the facts available, the project could compete with imported potash. We, ascertained that, although research in America suggested that this mineral had some value as a fertiliser when untreated, it could not yet be stated that it would be worth winning from this depth, or that if it needed further chemical treatment the final product would not be too costly 90 datog Hoodie Jedi Camol dick or olam of nov 20 20sutaminen biromab wo di woksurfhmas tubnele 205. In December, 1947, after further discussion with Dr. G. M: Lées, Professor S. E. Hollingworth and the Geological Survey at a special meeting, we decided that, subject to the results of further boring and pumping tests, a production of potash might be achieved more quickly and cheaply by pump- ing the brine solution which was proved at the base of the D'Arcy borehole (p. 44, v). Furthermore, we realised that the recovery of potash by this means would involve also the separation of about ten times the quantity of common salt, and that the economics of the project might be favourably influenced if the salt could also be used. There was also the possibility of natural gas, if it were found to exist in quantity, being utilised on connection with the pumping as a source of fuel in the extraction process, or being developed concurrently, for other, purposes.
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206. Dr. A. Fleck, a Director of I.C.I., later attended this meeting and his attention was drawn to the opinion we had reached. He admitted that up to that timeag€10 haft thought that the extraption of potash from the deposits was a proposition which would justify commercial development
45
34
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by them.
After this meeting, however, I.C.I. examined the brine-pumping scheme and subsequently wrote to us (February, 1948) that they thought the project heldgrufficient promise to justify further agploratory 6boring this they were prepared to undertake at their own expense. ghdadi tobiz
207. In March, 1948, we communicated our provisional conclusions to the Minister, emphasising that on the face of it, the brine-pumping scheme was more attractive than mining polyhalite. We stated that the prospect of proving thicker beds of "sylvinite must not be overlooked as this was potentially much more important.
208. I.C.I. commenced one exploratory borehole later in 1948 with the main objective of investigating the potentialities of the potassium-bearing brine. By February, 1949, when this account was written, the borehole had been carried to a depth of 5,500 ft. but it had not adequately penetrated the limestone strata in which the brine had been found in the earlier borehole, and technical limitation of the only equipment at present available prevents the borehole being carried to a greater depth. No further informa- tion about the prospects of the brine-pumping scheme, therefore, has yet been obtained.
209. This latest borehole, however, has yielded other information of great value. Precautions were taken to obtain cores of the strata in which the potash salts were recorded in the original borehole, and we understand that indications of a substantial thickness of potassium minerals were obtained which are promising enough to justify further exploratory work. Further- more, it would appear that interest may again turn to the possibility of recovering potassium chloride either by mining or by a solution method rather than by pumping the deeper seated potassium-bearing brine.
.
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210. Though the magnitude in a geological sense and the economic im portance of this latest discovery have yet to be proved, and it may be as long as two years before sufficient additional exploration has been carried out, it looks as if the prospect is emerging of a most important addition to the country's natural reserves. As this is the first indication of the occurrence of a substantial quantity of a mineral highly valuable to agriculture the whole of our domestic requirements of which are at present imported, great significance must be attached to this information.
211. If the most sanguine hopes of this project are realised and it is found that sufficient potash can be produced economically to make a sub- stantial contribution to our domestic requirements or even to make the U.K. self-supporting in this respect, then the question of whether one firm could or should embark on an undertaking of such national importance ought to be examined. Furthermore, the development of such a project whether or not it be undertaken by more than one firm, should be properly planned and related to information about the extent and importance of the mineral occurrence as a whole.
212. In the meantime, now that more specific information is available about the extent of potash deposits it is urgently necessary that further boreholes should be sunk in order that the extent and economic value of the occurrence can be determined and the most suitable method of development in the national interest be ascertained. Until the proposed Mineral Develop- ment Commission (see Chapter XI) is set up the national interest in project of this importance should be secured by some form of joint company with a controlling state interest, but in which other firms who might be
Per he interested in potash production in this country should be given the oppor- tunity of participating under suitable arrangements.
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213. We also recommend that, unless our proposals regarding the estab- lishment of a Mineral Development Commission and the nationalisation of mineral rights age 72 0 implemented within a short time, the mineral rights in specified potash-bearing minerals shall be nationalised separately, and without delay, in the same manner in which petroleum mineral rights were nationalised under the Petroleum (Production) Act, 1934.
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SALT
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214. The principal salt deposits worked at the present time in Great Britain are in Cheshire, Lancashire, South Durham, Staffordshire and Worcestershire. Cheshire production contributes over 80 per cent. of the total. A considerable part of the industry, operated by Imperial Chemical Industries Ltd., is concerned with the production of brine as a basic raw material for the manufacture of important heavy chemicals as well as for the manufacture of domestic salt. The remainder of the industry is mainly concerned with the production of brine from which salt is extracted for use in the food industries and for domestic purposes. The tonnage of rock salt produced is small; it is mined at one locality only and is sold mainly as cattle-lick.
Production
.
215. The annual output of salt in this country has for many years past been of the order of 3 million tons in brine, of which about 800,000 tons is extracted as solid salt, together with some 20,000 tons of mined rock salt, the U.K. normally ranking with Germany and Russia as the major world producers of salt after the U.S.A.
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216. In the period of the last War output of brine salt expanded and reached a maximum of 3.6 million tons in 1942. On the other hand the output of rock salt which had been as high as 215,000 tons in 1913, had by 1931 fallen to the order of 20,000 tons, and remained at that level until 1947 when it was almost exactly doubled.
TABLE XVII
PRODUCTION OF SALT IN GREAT BRITAIN
(tons)
*Brine
Rock Salt
Brine
Rock Salt
Rock
*Brine Salt
1913
1919
2,033,185 14,573 | 1928 ... 1,696,653 | 90,938 1929
1,914,969 31,349 1938
2,610,048 19,658
1,938,011 36,159 1939
3,180,715 23,323
1920
1,931,007 108,083| 1930
2,042,541 25,023 1940
3,351,830 26,022
1921
1,270,458 35,712 1931
1922
1923
1924
1925
1,888,973
1926
1927
1,736,081 36,548 1932 1,837,968 | 48,914 1933 .. 1,992,308 53,454 1934 ..
44,617 | 1935 1,686,753 | 40,690| 1936 ... 1,953,890 29,596 1937
1,876,011 21,553 1941 2,196,632 | 19,567 2,342,579 21,596| 1943
3,369,407 22,926
1942
3,570,589 26,968
3,353,684 21,174
...
2,499,025 20,848 1944 2,680,553 19,539 1945 2,800,297 17,291 | 1946. 3,052,518 18,371 1947.
3,355,104 17,490
3,217,552 | 16,792
3,333,039 20,490
3,099,302 39,997