GOLDMINING

Grey River Argus, 2 August 1940, Page 5

GOLDMINING

WEST COAST INSPECTION DISTRICT

G, W. Lowes, Inspector of Mines, reports:—

Buller County

Mokihinui District.—Red Queen Mine: Crosscutting, on the low level at 513 ft., encountered the Red Queen lode at 35 ft. west and. the Swastika at 136 ft west, the former being 7 in. wide and carrying high values with free gold showing, the latter being 48in. wide between walls which enclosed a mixture of quartz and reef track which assayed 4 dwt. per ton. At 159 ft. from the portal, a crosscut 54 ft. in length intercepted the Red Queen lode, which was 8 in. wide and of high grade. This lode was driven on for 18 ft. south of the crosscut, width and value being maintained, and the two crosscuts on this level have established the fact that the lode channel is approximately 400 ft. in length. Surface trenching at a lower level disclosed the ore channel at a point farther north than the development work in the upper levels. Lyell District.—Alpine Mine: Two hundred and three feet of crosscutting was carried out on No. 7 level through intensely hard rock, but nothing of economic importance was discovered; consequently, it was decided to abandon the mine and withdraw all rails and pipes at the end of the year. Inangahua County Blackwater Mine.—The total development footage amounted to 3,286 ft., as per the following summary: Driving, 2,272 ft.; rising, 407 ft.; winzing, 502 ft.; crosscutting, 105 ft. Results from the main development points were as follows:— No. 11. Level Drive North: This drive was continued on the reef north of the Prohibition fault for a distance of 209 ft., of which 200 ft. were on reef averaging 11.15 dwt. over a width of 2fiin. No. 12 Level Drive North: This drive was restarted, and continued along the Prohibition fault until the reef was encountered. Further driving exposed 99 ft. of reef averaging 14.56 dwt. over a width of 32 in.

No. 13 Level South: This drive was advanced 374 ft., of which 360 ft. exposed reef averaging 11.52 dwt. over a width of 32 in. No. 13 Level Drive North: A branch drive was put out to the west of the north end of the main drive in order to locate the reef north of the Prohibition fault on this level. The rfeef was intersected after driving 71 ft. in country rock and through the fault and by the end of the year 35 ft. of reef averaging 31.91 dwt. over a width of 38 in. had been exposed.

No. 14 Level Dllive South: This drive was advanced 725 ft., of which 580 ft. exposed reef averaging 17.60 dwt. over a width of 29 in. No. 14 Level Drive North: This drive advanced 432 ft., of which 366 ft. exposed reef averaging 15.52 dwt. over a width of 27 in., and reachen the northern limit of the main ore body at the Prohibition fault. The reef in the bottom of the mine continues to show up well. No shaft-sinking was carried out during the year, but a considerable amount of work was done on the Nos. 11, 12 and 13 levels north to locate and drive on the reef north of the main Prohibition fault and results obtained were most encouraging.

Ore reserves at the end of the year Showed a total of 102,349 tons, being an increase of 10,702 tons over the figure for the previous year. A new hydro-electric plant was erected near the site of the old battery, utilizing the water previously used to drive the old battery, and was put into commission during the month of May. The 1,000 cubic feet steam-driven compressor at the north shaft was completely electrified, and has been in service since the early part of 1938.

Alexander Mine.—No. 5 intermediate level, 80 ft. above No. 6, was extended the full length of the ore body, which maintained its average width, value, and length of 260 ft. The stopes above this intermediate level have yielded most of the ore milled during the year, and tonnage treated was 1,096 tons in excess of that milled in the previous year.. On No. 6 level the country was found to be much disturbed, and considerable difficulty was experienced in locating the reer. A considerable footage of driving in the lode channel and crosscutting into the foot and hanging walls was carried out before the first block was discovered. This block, although carrying high values, was short and narrow with a flat dip. A rise from No. 6 was put up on the ore chute, and at a point half-way between the] main and intermediate levels the lode was faulted. A sub-level was driven on the fault-line and several disconnected lenses of ore located, but it is evident from the amount of development carried out on and above No. 6 level that the present horizon of the mine is in country that has been subject to strong faulting. Big River Mine.—The following stoping and development operations were carried out:— No. 5 Level: A winze was sunk to a depth of 39ft. on a narrow orebody which cut out at the depth stated.

No. 6 Level: A considerable distance was driven on the lode channel. but only one small lens of very rich ore was discovered. Crosscutting in the walls of the ore channel disclosed that this level had been affected by earth movements which had displaced the lode between Nos. 5 and 6 levels. Development on this horizon in the earlier period of this mine’s history had the same result as the present work, and proved that this zone is unproductive. On the small rich chute discovered in No. 6, a rise was put up to connect with a winze sunk from No. 5, but the ore cut out a short distance above the level,, and the rise will be continued through country rock until the connection is established that will provide an air-course and travelling-way, A winze was started on 12 in. of rich ore exposed in the floor of No. 6 and eventually reached a of 74 ft. The width of ore gradually increased until a maximum of 60 in. was dis-' closed, with values maintained. In j order to expedite the development of! the ore-body proved by the winze, it M'as decided to retimber the main shaft down to No. 7 level, and, despite the shortage of skilled labour and inability to work more than a j single shift, a depth of 74 ft. had, been reached by the end of the year, i New Welcome Gold-mining Co.—A party of five men have driven on hand

steel the low-level tunnel a distance of 801 ft. from the portal through hard greywacke. At 450 ijt. a lode 60in. wide was met, but proved to he. barren' wfien sampled and assayed. This drive should' reach, its objective during the coming year—namely, the west reef of the Boatman’s main lode.

Lankey’s Creek.—Watts and party who operate this mine produced 260 tons of cemented gravels yielding 52 oz. 14 dwt. of gold, which realised £438 19s 2d. A considerable part of their time vyas spept on development work which' became necessary owing to an upthrow fault being encountered, and this increased the difficulties of mining and transport to such an extent that wash worth £1 per ton became unpayable. Murray Creek Mine.—During the year* an overhaul of the - winding plant .was commenced, a two-stage compound steam-driven air-compres-sor installed, and a new head-gear erected. No underground work was carried out other than draining the mine and preparing the main shaft for the sinking of another 150 ft. lift.

State-controlled Prospecting Operations. Globe-Progress Area.—Perseverance Mine: After the restoration of No. 1 crosscut was completed and the lode in the floor of the main levei sampled a winze was sunk to a depth of 74 ’ft.’. of which 60 ft. was on solid reef and the remainder on track with veins of quartz. On No. 2 level a total distance of 719 ft. was driven and crosscut without encountering the lode. In order to facilitate the search, a rise was put up through country rock to connect with the winze sunk from No. 1 and to drive an intermediate level 70 ft. above No. 2. The intermediate level was driven on reef for a distance of 205 ft., and at the north end of (the block a winze will be sunk on the lode to No. 2 level and the main level continued until it holes into the winze and then along the reef to its extreme north end.

Golden Treasure Mine.—The Perseverance crosscut was extended 1,800 ft. and holed into the Treasure shaft, which was proved to be 308 ft. deep from collar to floor of chamber at No. 3 level. The cleaning-out and retimbering of 650 ft. of No. 3 level was completed, also some crosscuts of old workings were made accessible for the purpose of gaining information concerning the structure of the country. Four hundred and six feet of driving and crosscutting were carried out in the north end of the mine on the lode channel and east and west walls, and entry was effected to some of the upper workings by repairing a rise put up from No. 3 and a winze sunk from an intermediate level situated below No. 2. It was ascertained after examination of the mine above No. 3 that the ore-body of considerable width and unknown length had not been worked to any extent below No. 2 level; consequently, when this ore-body is developed on No. 3 level a considerable tonnage of ore will be available for treatment if values justify it being mined. The development work was carried out by contractors using modern rock-drills. Grey County On the cessation of State subsidised prospecting operations in the Paparoa Ranges and the Moonlight and Langdon’s Creek districts at the end of 1938, lode mining came to a standstill in the county, and no activity in this direction has ensued during 1939. Westland County Locle prospecting was carried out at Totara Valley, near Ross, for a short period during the year, and no discoveries of economic importance were recorded. At the Seven-mile and in the Taipo Valley’ a party of men are engaged in prospecting lodes in the district. Greenland Gold, Ltd., Mount Greenland.—The new company installed additional treatment plant and treated a small tonnage extracted from stopes that were accessible when the claim was taken over. No development work was undertaken during the company’s period of activity, and the mine closed down in August and has not resumed operations. DREDGE MINING Mataki Dredge, Murchison County’. —This dredge, using 7-cubic-feet buckets, is one of the two steam-powered dredges out of a fleet of seventeen I operating in this district. Dredging operations continued upstream ini ground averaging 17 ft. deep. Mataki Junction Dredge Murchison County.—This Diesel-electric dredge working in ground of an average depth of 20 ft. dredged 681,000 cubic yards using 6-cubic-feet buckets. Worksop Dredge, Inangahua Countv —This small Diesel-power dredge dug the satisfactory figure of 421,500 cubic yards, from which was recovered 1,180 oz. 5 dwt., which realised £11.167 Ils Id.

Mossy Creek Dredge, Inangahua County.—During the year, this elec-trically-operated dredge, fitted with 4-cubic-feet buckets, treated 416,000 cubic yards from ground which averaged 11 ft. in depth. • Grey River Dredge, Inangahua County. — This electrically-driven dredge during its first year’s operation dug 4,500,518 cubic yards, from which was recovered 13,218 oz. 12 dwt., which realised £125,223. An average output of 87,500 cubic yards per week has been maintained by a crew ot thirty-five men operating the dredge in ground of an average depth of 25 ft. The dredge is fitted with 16-cubic-feet buckets. The maximum digging rate has been 744 cubic yards jv r hour, and the all-in cost came to 3.49! per cubic yard, expended to recover gravel of an average value of 6.680: per cubic yard. r the operations fori the months of January and February I were confined to digging a narrow cut along the eastern boundary of the area from the construction-site to a point south of the county road where | the dredge was turned in a westerly! direction and the cut opened out to about approximately 500 ft. in width. Three cuts were taken from east to west across a portion of the valley, when the transverse system of digging was altered to longitudinal digging, and a 550-ft.-wide cut was started towards the southern end of the i property. The close of the year found j the dredge digging about 1,600 ft. I from the south boundary of the pro-] perty. Except for some minor changes to machinery and gold-saving equip-] ment which would tend to improve the mechanical and metallurgical efficiency of the dredge, no major alterations were made in the original design. Argo Dredge, Grey County.—During the year this electrically-operateJ dredge, fitted with 4i-cubic-feet buckets and digging ground of an aver-1 age depth of 20 ft, and employing

thirteen men, recovered 2,263. oz. 13 dwt., valued at £21,075 10s 4d, from 605,800 cubi,c ya,rds. Blackball ' Creek Dredge, Grey County.—This dredge, operating on ground averaging 33 ft. in depth and employing twelve treated 580,000 cubic yafds from which 2,209 oz. 5 dwt., valued at £22,212 10s 7d, were recovered. The dredge is electrically operated and fitted with 5-cubic-teet buckets.

New River, Grey County.—This Die-sel-powered dredge, fitted with 4-cubic-feet buckets, dug 308,045 cubic yards in the New River, which yielded 1,498 oz. 4 dwt. of gold,” valued at £12,356 Os lid. Nemona Dredge, Grey County. — Operating in Cockeye Creek, this electrically-operated dredge, fitted with 4i-cubic-feet buckets, dug 400,30) cubic yards, which yielded 1,199 oz. 9 dwt. of gold, worth £ll,OOB Ils 6d. Bundi Dredge, Grey County.—This dredge operated on two shifts, employing fifteen men for part of the year, and dug 279,516 cubic yards for a return of 1,663 oz. 8 dwt. 23 gr., to the value of £12,224 4s 9d. Operations ceased on August 31, and offers were invited for the purchase of the company’s plant and dredging claim soon after this date. White’s Electric Dredge, Grey County.—Equipped with gold-saving apparatus suitable for the recovery of gold from the black-sand deposits at Barrytown, this electrically-operated dredge, using 4-cubic-feet buckets in 16 ft. ground, dug 335,420 cubic yards and recovered 1,458 oz. 9 dwt. of gold, which realised £11,645 12s.

Barrytown Dredge, Grey County.— The yardage treated by this dredge was 3,018.000, from which 8,928 oz. 4 dwt. 19 gr. of gold was obtained, the value being £75,032 0s Bd. The average depth of ground worked during the period was 30 ft., using 12-cubic-fee.t buckets, and difficulties were experienced on part of the area dredged due to encountering buried timber. Experiments with a pilot flotation plant were carried out with the object of increasing the gold recovery, exhaustive tests being taken, but the savings effected were not commensurate with the expense incurred in treatment; consequently, the idea of utilizing the flotation process was abandoned.

Ngahere Dredge, Grey County.—-A now dredge erected by the Railways Department’s engineering staff for the Ngahere Gold Dredging, Ltd’., was completed and had a trial run by the last month of this year. An area containing a large proved yardage of payable ground situated north of the Grey River and opposite Ngahere will give many years of dredging. The following details of the dredge were kindly supplied by the company’s manager:—

Construction: All steel. Electrically operated. The pontoon dimensions are: Length, 170 ft.; width, 72 ft.; depth, 12 ft.; and there are twentyeight water-tight compartments; total weight of hull, 600 tons. The diggingladder is 142 ft. 4 in. long between centres and weighs 1875 tons, the weight with rollers and bottom tumbler being 241 tons. The normal digging depth is 70 ft. at 45 degrees, and the maximum is 75 ft. at 48 degrees. These depths are below water-level, The dredge will dig to 104 ft. when carrying a bank of 29ft. The buckets are 18-cubic-feet capacity, and there are ninety-five on the band, discharging at the rate of twenty-two per minute. The buckets pins are Bin. diameter and the working weight of the band is 215 tons. The screen ; s 9 ft. diameter and 52 ft. 6 in. in length overall, and makes 5.92 revo-1 hitions per ’minute. Perforations:

Five bands 5-16 in. to 7-16 in., 1 band 3-8 in. to 4 in., one band 7-8 in. to 1 in. The stacker ladder is 203 ft. between centres, and the iconveyor

belt 44 in. in width. The dredge is spud operated with two spuds each weighing 53 tons. Gold saving is effected by short riffle tables discharging into Bendelari jigs, of which there are twelve four-hutch primaries. Con« centrates from primary jigs is pumped to two secondary .jigs, the first two hutches of which discharge to amalgamating plates, the remaining two hutches in each being in closed circuit. The total water-pumping capacity provided is 14,650 gallons per minute. The total motor horse-power provided is 1,573. The principal units are—Main Drive: Two 250 horsepower, one each side, driving througn Vulcan hydraulic couplings and Richardson gear-boxes. Ladder Hoist: One 250 horse-power, driving through Richardson reduction gear-box. Moor-ing-winch: One 80 horse-power, driving through Richardson reduction gear-box. Screen: One 100 horsepower, driving through Richardson reduction gear-box. High-pressure Pump: One hundred and seventy horse-power direct coupled. Lowpressure Pump: One hundred horsepower direct coupled. Hopper Pumps: Sixty horse-power direct coupled. Jigs: Two 40 horse-power and two 75 V-belt drives. Smaller motors operate cranes, footbridge, concentrate, and saveall pumps. The complete total weight of the dredge is estimated at 2,855 tons.

Maori Geld Dredge, Westland County.—Maori Gold, Ltd., formerly Maori Gully (Kokiri) Gold Dredging Co., Ltd., acquired and tested an area at Callaghan’s, south of Kumara, and re-crected the Nevis Diesel-electric dredge, which was purchased, dismantled, and transported from the Nevis 'Valley, Otago, to its present site. The re-erection was practically, completed by the end of 1939. Rimu Dredge, Westland County.— Operating in ground of an average depth of 53 ft., this electrically-driven dredge, fitted with 12-cubic-feet buckets, handled a total of 2,334,721 cubic yards for a return of 9,955 oz. 16 dwt. of gold, which realised £94,185. Kanieri Dredge, Westland County. —Despite breaks in dredging-time due to encountering old workings, with a subsequent lowering of water-level and renewals of plant, 4,776,000 cubic yards were dredged, and 14,700 oz. 2 d vl. 14 gr. of gold were recovered, which realised £124,279 9s lid. Arahura Dredge, Westland County. -Dredge-construction was completed by the New Zealand Railway’s Department’s engineering staff by the end of July, and on August 1 digging commenced. By the end of the year 1,600,000 cubic yards had been dug and treated for a recovery of 5,553 oz. 10 dwt. of gold, valued at £49,124 0s sd.

Okarito Five-mile Beach Dredge, Westland County.—A volume of 310.638 cubic yards of black sand were dredged for a return of 1,244 oz., which realised £10,096. Gillespie’s Beach Dredge, Westland County.—A broken working year due to the general overhaul of the dredge and attaching of auxiliary pontoons resulted in smaller yardage and decreased returns. Altogether, 546,636 cubic yards of material were treated for a return of 1,174 oz. 4 dwt., which realised £11,036 7s Sd. The Arahura, Ngahere, and Maori Gold Dredges were completed during the year, and the first-mentioned added to the total gold-production for 1939.

The Snow'y River Dredge is well advanced, and will be in operation during 1940.