THE PHOSPHATE GROUP

Wanganui Chronicle, Volume 74, Issue 144, 20 June 1931, Page 8 (Supplement)

THE PHOSPHATE GROUP

INTERESTING STORY OF MANUFACTURE PRODUCTS BROUGHT FROM FAR AFIELD It is continually being impressed upon us that the most important element of plant food is phosphate or to name it more correctly “phosphoric acid.” Phosphoric acid is derived from various sources but no matter what is the source f supply, the phosphoric acid utilised iu the feeding of plants remains the same. Considering the outstanding importance of the phosphate group of fertilizers, it should be worth our while to have a few minutes’ consideration to the sources of our supply.

SUPERPHOSPHATE

FIRST IN IMPORTANCE. Looking at a recently issued manufacturer’s price list we notice such lines as tho following—superphosphate, basic superphosphate, basic slag, North African phosphate, Nauru and Ocean Island phosphate, Seychelles Guano, blood and bone, steamed bonedust, Calcutta bonedust, all of which are com mercial forms of phosphoric acid. Now it is not our intention at tho moment to discuss the com rt-tive values of these forms of phosphoric acid but rather to give a brief account of tho origin of some of these commercial products. To start with it is not suggested. that our list already quoted covers tho entire phosphate group, there are other lines known commercially tha* are not included; but in the absence of any very definite information about them we must pass them by. First on the list and without doubt first in importance conies superphosphate or super as it is orc familiarly known. Super is what one might term a “manufactured” form of phosphoric acid, that is to say, there is a definite factory process of preparing and mixing several ingredients to the end that a high class fertiliser is produced. Three Raw Materials. Just imagine for a moment what is Involved in the manufacture of super! First there ’ the roc’’ phosphate from Nauru or Ocean Islands away up near the equator, next there is f > pure sulphur found at a depth of 1000 ft. or more below the surface of tho sunbaked plains of Texas, and then there is the nitrate of soda recovered from the rainless uplands of Chile. These three principal raw materials are brought together in this country where in up-to-date factories they are skilfully blended into that life-giving stream known to farmers and gardeners as “Super” 44/46 per cent, water soluble. We will not attempt a description of the processes through which the various raw materials pass until they are converted into super. We content ourselves by saying that these processes are necessary to render the phosphates contained in tho raw material available in water. In superphosphate we have tho only watersoluble and consequently the quickestacting phosphate on the market. Lime-Deficient Soils. Basic supherphosphate is simply a mixture consisting of 85 per cent, superphosphate and 15 per cent, burnt lime,—again a manufactured product designed to supply the requirements of lime-deficient s. ils. In actual practice it will bo found that basic super will give results approximately equal to basic slag. Basic slag is perhaps more correctly described as a by-product than as a manufactured article. When the iron and steel manufacturers wish to extract the phosphoric acid from the huge retorts of molten metal over their furnaces, they throw large quantities of lime into tho pots. Lime, as we are told, will collect the phosphoric acid out of tho molten metal and take in unto itself, holding it there and then forming a scum on the surface of the pots. The scum is cleaned >ff and thrown, to one side in heaps to cool into something approaching cinders or ashes in appearance. Later on this stuff is ground into a fine powder and then we have commercial slag. All slags arc not of equal grade and this is duo partly to varying processes adopted and partly to the varying grades of ore used in the manufacture of steel. This Dominion imports large quantities of slag, much of which, is of very low grade, but because it is slag, it all finds buyers. Natural Phosphates.

Now we have the group of raw or natural phosphates at the head of which stands Nauru and Ocean Islands. It seems to me that there are two very good reasons why New Zealanders and New Zealand farmers in particular should know something of the history and pote : alit,ies of these islands. The first reason is that we derive the bulk of our supplies of phosphate from there and the second reason is that we are. actually partowners in them. Nauru, which is the bigger of the two, lies almost due north of New Zealand and only about 26 miles south of-

the equator. The island has an area of about 12 square miles and it has been estimated that six-sevenths of this is phosphate bearing. This island of Nauru was discovered by Contain Fearn, in the British ship “Hunter” in 1798 and named Pleasant Island. It continued to bo known as Pleasant Island till 90 years later vzhe- in 1888 the Germans annexed it and reverted to tho native name of Nauru by which it continues to bo known. It seems rather strange that '"’uring the whole period of German occupancy of tho island—from 1888 to 1900—the presence of such beds of phosphate rock was not suspected. Apparently tho Germans valued thoisland as a trading port and as a source of supply of copra. At this time there was trading in the Pacific a company known as the Pacific I land Company, a concern with extensive business interests which included the working of guano deposits on various Pacific islands. Mr A. F. Ellis, New Zealand representative on tho British Phosphate Commission, and who now resides in Auckland, was then nngagec as anager, under tho Pacific Islands Coy. of an island jus', off the coast of Queensland. 2\fr Ellis was trasferred to the company’s Sydney office where there had been set up a laboratory for the purpose of dealing with samples of cargoes, etc. r Ellis’ attention was arrested by a large block of stone used for keeping tho laboratory door open and. on asking wl t this stone was, was informed it was a piece of petrified wood found on I’easant Island some three years before. Mr Ellis was not satisfied with this explanation even though it was supported by one or more noted geologists; so he determined to test it for himself and was not surprised to find that the door stopper was a piece of phosph 'e rock of tho highest q ility. The following up of this clue led to the closer inspection of both Nauru and Ocean Islands and tho locating there of huge deposits of high grade phosphates. When war was declared in 1914 Australia sent some troops to take possession of Nauru Island— Ocean Island was already a British possession—so that tho Empire once again had possession of what is probably the richest island of its size in the world. The total quantity of phosphate available ou Nauru and Ocean Islands is set down authoritatively at not less than 100 million tons still to be lifted. Coral Pillars Left. Tho phosphate exists mostly in a form and colour similar to our New Zealand gravel but here and there are enormous boulders that have to be split up with explosives. The phosphate docs not occur like a solid wall such as one sees in an ordinary stone quarry, but rather a filling between endless rows of coral pinnacles. A worked out field must be a strange sight with its myriads of coral pillars dotted irregularly over the surface. Chinese labour is employed in excavating and preparing the phosphate for shipment. The phosphat i is crushed to about the size of nuts, put through a drying process and then stored awaiting shipment. Writing in the N.Z. Journal of Agriculture in January 1928. Mr Ellis said that during the next three years New Zealand and Austr lia between them will require 100,000 to 200,000 tons more ph isphate annually than Nauru and Ocean Island can supply. Tho limiting factor i . drawing supplies from these islands is shipping facilities rather than available phosphates. It frequently happens that a steamer in the midst of her loadingoperations has to slip her mooring lines and make out to sea on account of sudden storms. Great improvements are in process of completion, however, and it may bo that the islands will again be able to meet all the demands the farmers of New Zealand and Australia care to make upon them.

Although tho Nauru and Ocean Island phosphates are high grade they are not very suitable for use by themselves in their raw state because of their insolubility, but they make the highest grade of superphosphate manufactured in the world.

Australia ami New Zealand take the output from these two islands, the total tonnage for the ninth year of operations under the British Phosphate Commission’s control being 576,590 tons or 25 per cent. At this rate of output it is said that the supply will equal the demand for the next 200 vears.