GOVERNMENT REPORT

Greymouth Evening Star, 22 February 1917, Page 5

GOVERNMENT REPORT

i LIMESTONE'* FOR AGRICULTURAL , PURPOSES IN WESTLAND. _. (Per favor of the iW Minister <'f .•-; Agriculture.)'. ;'..• The successful development of a'gfi- , cultural lime, whether ground 'or ", burnt,, requires not only the abundaint development of the proper materials for iti manufacture, bur. aluo closa proximity to transportation facilities whereby the lime may be economically distributed among customers, Only those places that could conform' with the -above considerations were* examined on thin occasion, and undoubted- - ly there are many localities not here mentioned where suitable material occurs 1 . A large proportion of the agricul- ' turnl land on the Wefet Coast, is coji- \ veniently situated" ,h#respect to the . railway, system, and any lime works situated cLf.e to ,the railway would readily serve this area. Greyniouth.—The lime deposits of Gi'eyinouth present many advantages, for not only w there an abundant supply of material, but two quarries with lTOlway-fridingfr and- cranes for handling large stones are already opened. The Grey River has cut a gorge through thick calcareous beds which strike nearly nortTi-eaiit and dip west, ward at about 30 degrees. On the fwuthern (or Creymouth) side of the liver ilie beds in which the quarry is opened are lower in the. sequence than those worked on the (or Cobden) side. The. inoiit promising layer shows. 20ft of limestone in beds from (iin to 3ft thick. separated by argillaceous partings l . A general sample across! -.this layer gave T'9.61 per feint of calcium-carbonate, i.k little youth of Greymouth, near Trig F.C., a layer of foraminiferal limestone occurs higher in the rook sequence than any layer yet considered. This bed is at leaut 20ft in thiols-■ ueiisj and outcrops along 1 the hill em;t lot; three chains. The dip \a .'SO degress, and the sample taken by the writer was found to contain <84.82 per ' cent, of calcium carbonate. Stone from this locality is reported, to have

been ''bumf." sucgesafully;' The deposit is about 20'chains from the nearest load, (50 chains from the (ireyniouUi railway station, uud above sea lcve.l, The' limestone beds, in "which are the Cobden and Greymouth quarries, form ranges of hills north and nouth of the river. The writer examined cliffs overlooking the railway line for about a mile. The stone here, howeve:', in appearance is of better general qtialfty thnii that quarried at GreymoutTi. . . .. * • .Stillwater.—About half a mile from the Stillwater railway station along the Ot'ira line limeatbho".outcrops in a, sidling cutting. Tlie exposure is not clear, but the calcareous rook, occurs cither as large as- concretions in sandstone., or «as fragments in-a fault-zone. The rock is evidently decidedly impure-

The limestone outcropping ia. Lisbon and Sylvester Creeks., small branches entering Stillwater Creek .between three and four miles above, its mouth, was also examined. Some of the layers in this locality are of high grade, but the difficulties of transport preclude ; their being. used at the present time. . . Inangahua Valley.—ln the Inanga-'hua.'-Valley, about five-miles from the Ropfton railway station, limestone of fair quality occur:!. ,'l\vo analyses are available, both, of which are of stone containing more than 80 per cent, of - caloium carbonate. It is doubtful, however, if a general sample would give so good a result, and in any case the distance of the deposit from the railway is too great. .' On "the Reefton-Westporfc Road.: near'lriangahua Junction,'.and about 100 chain;', from the railway station, a hard band.of. liinestqnojit. least 10ft thick occurs";"' Mr. H." Belts states .that tTii;;,. stone was "burnt" 4n a rpugh kiln' with £ood' re::ults" "years ago, and a sample taken' showed. BS.G(I per- cent of oalcium carbonate. In the bed of the first small creek north of the Landing 1 !) ridge and about <cm chains from the railway, limestone appears from beneath: heavy bedu of sandstone. , The amount .of stripping required in this locality is too great for cheap working, while the rock, judged by it*i appearance, is. rather impure. The same limestone layers outcrop further south iiii the streams draining to the Inangahua from the Paparoa Range. High-grade.:.liuie-«tone is known to outcrop in at least two streams, but the absence of roads and of a. bridge across the- Inangahua prevent these occurrences from bekig. utilised at the present,, time. Marsdeu—South of Grey mouth, limestone outcrops; not far from the old ''Limestone Diggings," north of Marsden, and hear an excellent timber tram that .reaches the railway. The stone, however, its decidedly argillaceous 1 at the spot where,it was examined.

i Rossi —Near Ro&s t the'spur between Hodson and Coal Creeks h va part formed of excellent limestone. An analysis of a sample collected by the Geological Survey in 1907 yielded 91.20 per cent of calcium carbonate. This'deposit is nearly 200 chains from •„ the railway. ■ Central Plant.—The above comprise all the limestone deposits,.reasonably close to the railway, examined o<n this occasion. If all are taken iuto consideration,, the lower layer worked in the Greymouth,quarry iwtll probably be> most -suitable as' a-1 sohlw of agricultural 1 ; limestone for chat, portion of the West Coast served by railway. The.rock' is rather impure amd? is* quite uilsuitedifor "btirnngj" •' \v.hile : the wearing parts, of any irusher used will require to b'e easily replaceable. It would probably, be idyisable'also roughly ■to ■ sort the' it one before crushing.■•' • . : . . Taraniakau Clear Creek," 40 'cliain'ii 'from road,; are*,? !.putci:o y ps'.".,bf impure limestone inter- • bedded-with .ciaystone,' limestohei and "conglomerate. Owing to the' heavy of' vegetation it '.was . impost 'iiblo to ascertain the exact relations >f iliese licSs or the amount of hmu\iW)& available.. , A sample taken, from several scattered outcrops. contained :

70.68 per,.cent of calcium carbonate, ■■; while.. :-.9rie'.takeli some yearn ago by P. G. Morgan yielded 6486 per cent. On the spur to the north, stone occurs of better quality, ay far as ap-pearance-goes, ■■■than'that exposed in the creek. ■ - COST OF QUARRYING AND CRUSHING LIMESTONE. In gqfreral, 'under New Zealand conditions:, limestone ought to be quarried 'and.transported to an adjoining .crushing plant for le&» than 4s per ton (including- interest on capital, depreciation, etc.). In America, .in large works, limestone is delivered to the rook-breakers at from Is 3d to lu 'Od.per ton. ■As-to.'the cost of crushing, nothing definite can be said, because little information is oin record concerning the cost of thia operation in small plants. In many cases the wear and tear of the machinery employed will be a terioug, item. A most important factor is the nature of the demand, whether large or small, continuous or intermittent- If a large continuous' demand for crushed limestone could be asjumed, with a properly-designed plant hard rock could be ground to coarse powder for less than 2s per ton. a figure, however, that does not include wear- and tear on machinery or interest on capital cost. Perhaps a fair estimate of the real coat of grinding limestone on a moderately hvrge scale is about o» per ton, while if drying is necessary, agi will be. the ease when the stone contains more than two or three per cent .Or moisture, tid more per ton must be added. On the small scale suitable to mo«t fanning districts" it is. not likely that the covit of pulverising limes'one would be less than, about double Unit just mentioned, or, say, 6s- to 7s per ton. This, estimate is intended to include interest on capital, repairs, depreeia-'' tipn, etc. Bad management, unsuitable plant, impure limestone, or an intermittent or irregular demand might easily add another ;5s or 4s to the working cost. It may, however, be considered that in all but the mout unfavorable .sit uationSj lli» per ton should cover the total cost of quarrying and pulverising. In some parts of the United States crushed limestone . can be placed Upon'.railway trucks for

2ij Gd per tun,: un'4 it* anywhere ki Mew Zealand the: cost ia found to'exceed the estimate "of 10,s per ton given above, it in clear some reorganisation of methods is necessary.' It may be of interest to explain how the estimate of the cost of pulverising Im-iestone was arrived at. Gold-bear-ing quartz is; crushed on a large srxile it Wailu a!nd Reef ton. Crushing aided i>y the addition of water, which enxblea the stamps! and other machinery o produee a greater output than if : he quartz Mere crushed dry, as would i jo the case with limestone. The comlarative '•.'softness of limestone, how■ver, will enable it to be crushed dry it no greater coat than quartz when uilverised by the wet process. At iVaiiii the cost of transporting the ore ev-eral miles and reducing ir to pulp, if which 70 per cent is slime, is a it-tie under 2h Gd per ton, while at Reefton ore is crushed to pass a mesh of 15 holes per linear inch at a cost that varies at different milis from 1:: 8d to 2s od per ton. It must be note'd that all the plants referred to' treat over 2000 tons: per month. (Surnerl'i J ANDERSON. December -19 th 1 , 1916.