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By C Hall, J L. Mauk

New 40Ar/39Ar dates of vein and wall rock adularia from seven epithermal deposits and one porphyry copper prospect help constrain the ages of mineralisation in the Hauraki Goldfield. Vein adularia from the Paritu region yielded a single 40Ar/39Ar plateau date of 16.315 ¦ 0.066 Ma. Five 40Ar/39Ar plateau dates of three samples of vein adularia from the Opitonui deposit overlap within error to yield a preferred age of 13.149 ¦ 0.016 Ma. Two samples of vein adularia from the Night Reef at the Broken Hills deposit yield exceptionally flat 40Ar/39Ar plateaus, and all dates overlap within error to provide an age of 7.121 ¦ 0.010 Ma. Two 40Ar/39Ar plateau dates of one sample of vein adularia from the Wharekirauponga deposit overlap within error to provide an age of 6.318 ¦ 0.061 Ma. Four 40Ar/39Ar plateau dates of three samples of vein adularia from the Maratoto deposit overlap within error to provide an age of 6.411 ¦ 0.022 Ma. Two samples of adularia from altered wall rock at the Sovereign deposit yield three 40Ar/39Ar plateau dates that range from 6.547 ¦ 0.021 to 6.806 ¦ 0.028 Ma. This suggests that mineralisation formed around 6.6 Ma, but the results are complicated because the adularia contains minor illite that post-dates adularia formation. Results from the Karangahake deposit are complex. Two samples of vein adularia yield three 40Ar/39Ar plateau dates that range from 6.116 ¦ 0.116 to 6.901 ¦ 0.101 Ma, whereas one sample of wall rock adularia that contains minor late illite yields two 40Ar/39Ar plateau dates that overlap within error to provide a date of 5.734 ¦ 0.041. The range of dates indicates that more work is necessary to understand the history of mineralisation at this deposit. Two samples of vein adularia from the Tui deposit yield four 40Ar/39Ar plateau dates that overlap within error to provide an age of 5.714 ¦ 0.017 Ma. These results confirm previous work that indicates that the ages of epithermal deposits young southward in the Hauraki Goldfield. These results are also consistent with previously postulated different ages for deposits hosted in Kuaotunu Subgroup rocks in the northern goldfield (>10 Ma), and deposits hosted in Waiwawa Subgroup rocks in the southern goldfield (7.1 to 5.7 Ma).

Jan 1, 2005

DESCRIPTION OF OREThe ore consists, in general, of a very finely grained mixture of sphalerite, galena, and pyrite, with a gangue of quartz and schistose material, and contains about one ounce of silver to the unit of lead.Minor minerals are chalcopyrite, tetrahedrite, and ruby silver. The amount of gangue within the ore-bodies themselves is usually less than 20% of the weight of the whole. The ore is banded in a way that corresponds to the structure of the original schists, and is by no means uniform in composition-at one point, for example, blende may predominate, and a few feet farther on the body may become highly pyritic.Owing to the intimate association of the mineral constituents of the ore, it is very difficult to separate them from one another.Although this remark applies to ore from all parts of the field, the difficulty is particularly noticeable with Rosebery ore, the minerals of which are more intimately mixed, and are of smaller grain size than are the minerals of the Hercules ore.To effect a reasonably clean separation, it is necessary to grind the ore so that 90% passes a 200-mesh I.M.M. screen. Microscopic examination of the crushed product shows that 85% of the minus 200-mesh material is less than 30 microns in diameter, or, in terms of screen sizing, is minus 400 mesh. Particles under 30 microns are found to consist, of one mineral only, but in particles over this size separation has not always been effected. For instance, it is known that part of the galena and of the pyrite in the zinc concentrate is associated with sphalerite, and that part of the galena in the mill residue is associated with pyrite. There is only slight association between the minerals in the lead concentrate.

Jan 1, 1927

Evaluation of the Iron Blast Furnace Process using Heat and Material Balances of the Flame-Zone

Sep 13, 2010

By R J. Worland, D Bowyer, J L. Mauk

The TerraSpec is a compact field portable mineral analyser that uses non-destructive reflectance spectroscopy for mineral identification. The instrument uses and measures infrared and visible light that is absorbed by certain covalent and molecular bonds (AlOH, FeOH, MgOH, CO32-, OH, H2O and NH4) within the lattice of a mineral at specific wavelengths producing an absorption spectral profile. A variety of minerals can be detected including clays, micas, carbonates, and hydroxides as well as some sulfates and silicates. However, not all minerals are detectable, such as quartz and feldspar. Alteration minerals replacing volcanic rocks have been studied for several epithermal prospects in the lower Waitekauri Valley (Sovereign, Jubilee, Scotia and Jasper Creek) and a geothermal field in the Taupo Volcanic Zone. At the Sovereign, Jubilee, Scotia and Jasper Creek prospects previous XRD investigations determined well developed clay mineral zonation with illite in the west (Sovereign and Jubilee) grading into interstratified illite-smectite (Scotia) and smectite (Jasper Creek) to the east. Although the percent of illite within interstratified illite-smectite could not be determined and some illite-rich illite-smectite (>90 per cent illite) and some smectite-rich illite-smectite (>90 per cent smectite) could be misidentified as illite or smectite respectively, the TerraSpec survey determined the same zonation of illite to illite-smectite and smectite. Common chlorite, rare calcite and local kaolinite were also detected. At the geothermal field, the TerraSpec was primarily used to determine the occurrence of kaolinite, dickite and alunite, which form in acid conditions. Widely spaced (every 50 to 100 m) XRD results are in excellent agreement with closely spaced (every 5 to 10 m) TerraSpec results that further determined the occurrence of these minerals in previously unrecognised intervals. It also determined the occurrence of zoned smectite, illite-smectite, illite, and chlorite alteration. Overall, the TerraSpec is a rapid mineral identification technique that is very useful in delineating the occurrence and distribution of certain minerals in both epithermal deposits and geothermal fields. Although the TerraSpec cannot detect as many minerals as XRD, the TerraSpec allows data collection at a sampling scale and speed (real time) that is not practical by XRD.

Jan 1, 2006

By Kennedy G. L, Evans D. G

The development of the carbonization of brown coal briquettes to produce a hard char suitable for use in place of imported hard coke has continued in Victoria, and an experimental carbonization plant has recently been commissioned at Morwell by the Gas and Fuel Corpora.tion to assess the prospects for the commercial production and marketing of hard char in Victoria. The char offers advantages in its very low ash content and its uniform lump size, while the indications are that it could be marketed at a price competitive with that of imported hard coke. The hard char is unique amongst metallurgical fuels in combining a high reactivity with high physical strength, and research by the University of Melbourne into its utilization in foundry cupolas for melting iron has shown how modifications could be made to take advantage of these properties. An 18 inch experimental cupola has been built to test in practice the predictions made from this fundamental research.INTRODUCTIONSteady development has continued in Victoria from the promising laboratory researches at the University of Melbourne which were reported to the 1955 Annual Conference of The Institute (Worner, 1956). This work had shown that a hard lump char could be produced by the high temperature carbonization of standard industrial briquettes by careful control of the heating conditions, and that the special briquetting techniques adopted in Germany were unnecessary with Yallourn brown coal. Continuation of this research has led to the refinement of carbonization techniques and has increased the strength of the char until it has equalled that of conventional metallurgical cokes.

Jan 1, 1960

By Wilson A. F

The use of stable isotopic measurements as a technique for elucidating the origin and history of the water in hydrothermal fluids is relatively new. Recept studies have emphasized the importance of meteoric water in the formation of many hydrothermal ore deposits including many epithermal gold-base metal deposits which occur in faulted volcanic terrane. Other vein-type gold ores are believed to have formed from fluids of magmatic or metamorphic origin and exhibit characteristic d18O values. Preliminary oxygen and carbon isotopic data for some important gold deposits of eastern Australia have emphasized the diverse origins of their ore fluids.The Mount Morgan gold-copper orebody is shown to be of the volcanogenic massive sulphide type with ore fluids predominantly of sea water origin. The Charters Towers fissure veins formed during hydrothermal activity associated with intrusion of Lolworth Igneous Complex equivalents. Oxygen isotopic studies of the quartz reefs at Stawell and Gympie have been inconclusive. The ore fluids have a d18O value of about 7 per mil and may be of magmatic or metamorphic derivation.

Jan 1, 1981

The latest outcome of science is that aII bodies are composed of vibrating atoms or molecules. In almost all mineral bodies when changing from the gaseous or liquid condition to the solid, if the vibrating molecules are allowed free play, they arrange themselves in a symmetrical manner, and at a definite angle to each other: This angle varies with each system of crystallization. In a great many bodies this process may be brought about artificially, and the growth of the crystal watched. The most common method is to dissolve some substance in water or some other liquid, on slowly evaporating the liquid, the substance dissolved will solidify and the molecules will arrange themselves in their particular crystalline form.The element carbon crystallizes in two forms; as graphite in the form of a short six-sided prism', and in the diamond generally as the octohedron in the cubical system of crystallization. Orystalline bodies, as a rule, have plain faces but what is remarkable in the diamond is that in a great many cases the faces are rounded. Its great beauty as a gem when cut, and the high artificial value placed upon it by fashion, as well as its value as a cutting and boring instrument-it being the hardest body in nature-has caused many attempts to be made to form it artificially. These attempts have met with fair success as a scientific experiment, but as a commercial speculation they have been a complete failure. The most noted of these experIments was carried out by Mr. Hannay, of Glasgow.Paraffin spirit with lithium was submitted td prolonged heating in strong wrought-iron tubes securely welded. In most of the experiments the tubes exploded; but in a few cases the experiments were successful, and on cutting open the tubes small crystals of diamonds were found embedded in a black mass.Despretz produced minute diamonds under the influence of a powerful electric current from coal.

Jan 1, 2004

The flolation behaviour of some Australian uranium ores was investigated. Although uraninite and pitchblend float readily with fatty acids, selective concentration to produce an economically discardable tailing has not yet been achieved. This is attributed to the presence in the ores of a quantity of uranium mineral in finely dispersed form which is very difficult to liberate. For some of the ores, at least, the proportion of this material decreases with increase in head assay.Flotation may be a useful concentrating method for some Australian ores if uranium oxide is to be sold in a free competitive market.

Jan 1, 1967

Five types of mineral resource were known in the sedimentary cover of the oceans and seas floors prior to the 1980s: 1. hydrocarbon fields including some very large zones of oil and gas accumulation; 2. æRed SeaÆ type thermal oozes with increased concentrations of noble metals; 3. ferromanganese nodules; 4. concentrations of metallic sulphides (æBlack SmokersÆ); and 5. cobalt-bearing ferromanganese crusts on the summits and slopes of seamounts.   Since then, the so called æWhite SmokersÆ, containing sulphides of copper and zinc, have been discovered. The ore horizons (manganese, copper, nickel and other metals) of the sedimentary cover of deep-sea basins comprise a sixth type of mineral resource in the oceans. These horizons have not only a theoretical, but also a principal economic significance.

Jan 1, 1995

The effect of conditioning energy input on the metallurgical results of an emulsion flotation process has beenattributed by previous authors to a detergency process.This paper shows that such a process does not explain the data and that an attrition mechanism is more appropriate.

Jan 1, 1970

It has been fairly firmly established (Fisher, N. H., 1945) that the fineness of the gold in any ore deposit varies with the depth from the surface at which the deposit was formed, and, as a corollary to this, that it is dependent upon the temperature and pressure at the time of deposition. This relationship is such that, under certain conditions, the gold fineness, taken into consideration with other recognised criteria, furnishes a very sensitive and reliable guide to the relative temperature of ore formation, at least within the epithermal and the upper part of the mesothermal range.Definition of Fineness.The fineness of gold is calculated in parts per thousand and refers to the proportion of gold present in the naturally occurring metal in the lode, which is actually a gold-silver alloy, containing usually about 10 parts per thousand of base metal and up to 500 parts perthousand of silver. A clear distinction should be made between fineness and gold-silver ratio. The latter refers to the total gold and silver in the lode as determined by assay and is usually expressed as the ratio Au:Ag. Only in deposits where other silver-bearingminerals are entirely absent, which occurs comparatively rarely, can the gold-silver ratio be used as a measure of gold fineness and, in many cases, the two have no relationship. For instance, in the Edie Creek area in New Guinea, the lodes formed under shallow epithermal conditions all carry gold 500 to 550 fine, although the gold-silver ratio ranges from 1:100 to 1:1, in places in adjacent lodes.Determination of Gold Fineness.The fineness of lode gold can be determined only after it has been separated from all other minerals. Amalgamation recovers gold fairly cleanly - unless native silver is present - and the fineness of amalgam bullion is generally a reliable indication of the correct fineness of the gold. If the use of plates is involved, the bullion may be adulterated, but the effect of any copper, or other metal, that may have been introduced can be cancelled by assuming that the gold and silver shouJrl add up to about 990 fine, or by ignoring the base metal content altogether, which varies little in naturally-occurring gold, and in calculating for comparison purposes all fineness figures to the basis Au + Ag = 1,000.The composition of bullion obtained from cyanidation is generally intermediate between the true gold fineness and the total gold-silver proportion as determined by assay of mine or mill-head samples of Cyanide solution dissolves other silver-bearing minerals and the fineness of the resulting bullion is thereby lowered. Consequently, the fineness of cyanide bullion rarely corresponds to the true gold fineness and is useless for diagnostic purposes, although it is a common fallacy to refer to the fineness of cyanide bullion as the fineness of the gold.

Jan 1, 1950

S. R. Carter (Mount Isa Mines Ltd., Mt. Isa): I found many ideas to interest me in Haddon King's paper "Notes on Ore Occurrences in Highly Metamorphosed Precambrian Rocks" (Stillwell Anniversary Volume).At Mount Isa I have not been happy about some of the longstanding appreciations of the geological evidence as fresh data accumulated, and as more and more knowledge has been building up outside Mount Isa in recent years of sedimentary deposition of sulphides.Accordingly, I organized a small section of the Geological Department at Mount Isa at the beginning of 1958 under Senior Geologist, W. J. Murray to reappraise our geological record and investigate old interpretations and new ones that arise. The work is expected to take several years to complete, but it is hoped that sufficient will be done before then to permit the most plausible story on the ore genesis to be chosen. In the meantime, W. J. Murray has proposed, in a Company Report, that the.epigenetic features of the silver,lead-zinc deposits, which are essentially conformable with the shales, could have resulted from remobilized syngenetic deposits.Haddon King, on p. 159; has listed six assumptions that are required by a magmatic-hydrothermal theory of, origin for conformable deposits. It is interesting to consider the Mount Isa silver-lead-zinc deposits in terms of these requirements.My comments are listed in the same order as Haddon King's assumptions:(a) "The source of the constituents is magmatic and they have become available in successive waves of zinc-rich, lead rich, manganese rich, silver rich, etc, instalments in accord...

Jan 1, 1959

By Harris J. W

The treatment plant at The Great Boulder Proprietary Gold Mines Limited was designed and erected by Chas. Ruwolt Proprietary Limited in 1934 to mill 12,000 short tons per month. The flow sheet called for fine grinding, straking, flotation, roasting of the flotation concentrates and cyanidation of the resulting calcine.In 1937 considerable alterations and additions were made to the plant. The grindin,g section was duplicated with addition of two 8 ft. x 6 ft. Abco Ball Mills to increase the throughput to 28,000 tons per month, and the flow sheet was changed from "straight flotation" to "precyanidation and flotation" neeessitating the addition of thickeners, agitators, Oliver filters and Edwards roasters.A further change to the flow sheet was made in 1942 with the introduction of sulphur dioxide conditioning ahead of the flotation section, to permit the treatment of 500,000 tons of oxidised ore. Since that date no major alterations were made to the flow sheet or equipment until 1950, when the modifications set out in this paper were commenced with the object of reducing costs and increasing plant efficiency.These modifications are dealt with under the section headings and are therefore not necessarily in chronological order.CRUSHING SECTIONThere has been no material alteration in this section although at the time of writing a 650 ton capacity ore bin is being erected ahead of the primary Jaques crusher. This bin will reduc'e the crushing time from a three shift to a two shift basis and reduce the labour force required by two men, giving an annual saving of £2,000.FINE GRINDING SECTIONAlterations to the grinding section were commenced in 1950. Prior to this date the grinding flow sheet calle...

Jan 1, 1955

By J L. Mauk

The Gladstone Hill area hosts epithermal veins similar to those at Martha Hill, which is less than one kilometre away. There are several vein types in the Gladstone Hill area including (1) pyrite-marcasite, (2) quartz, (3) base metal sulfide, and (4) calcite. Pyrite veinlets formed first, whereas the quartz and carbonate veins formed later. The base metal sulfide vein occurs at depth and is predominantly comprised of quartz and chlorite intimately intergrown with pyrite, sphalerite, galena, and rare chalcopyrite. Platy calcite and massive calcite veinlets were the last vein types to form. Several vein textures occur in the Gladstone Hill area, including colloform and crustiform banding, lattice-bladed, zonal, comb, massive and feathery textures. Crustiform banded veins are the dominant texture and contain variable gold-silver grades. Colloform banded veins consist of ubiquitous quartz and minor chalcedony with gold grades as high as 60 g/t. The lattice-bladed texture forms from the deposition of calcite, which has been replaced in many samples by quartz, indicating that boiling and later cooling has taken place. Unreplaced platy calcite only occurs at deeper levels (>300 m). Zonal and comb textures are preserved in quartz and late-stage amethyst veins. Feathery textures within quartz are commonly associated with breccias and some colloform banding, and with significant Au-Ag grades.   The homogenisation temperatures (Th) of primary and secondary inclusions in quartz, amethyst and platy calcite range from 166 to 274¦C, with salinities <1.3 wt% NaCI equiv. The presence of vapor-dominated inclusions and primary fluid inclusions in platy calcite suggests that boiling occurred intermittently throughout deposition. The veins formed under a relatively flat lying paleowater table that occurred 280 - 300 m above sea level. The fluids involved in vein formation were alkali chloride in composition and low in CO2.

Jan 1, 2001

By K L. Brown, J L. Mauk

Sulfide-rich scale occurs in steam and water lines at the Ohaaki geothennal field,Taupo Volcanic Zone, New Zealand. Precious metals show very high concentrations around areas ofpressure reduction (Au 15500 ppm, Ag 68800 ppm). Pyrrhotite dominates at the orifice plate due to low PH2s1PH2 conditions. Sulfide mineralogy in the scales is consistent with alteration mineralogy of the reservoir rocks. Separated steam then produces a mainly pyrite/magnetite mineralogy, with lesser chalcopyrite, where textures reflect high flow rates and high levels of supersaturation. This study outlines the effect that pressure and subsequent temperature decreases have on the mineralogy, chemistry and textures of sulfide scales.

Jan 1, 1998

The importance of timbering, not only from a financial point of view but from an actual mining point of view, is so often overlooked or slightly glossed over by the average expert and investor, that I have thought it would prove interesting to go into the matter and to invite discussion upon the subject. We will first take small veins, or reefs as they are termed in some mining countries; and by small veins it is intended to denote fissures from a few inches to three feet. The ore body is supposed to be confined within well defined walls free from gangue matter, unless the casing can be defined as such. Now, if the walls are smooth and moderately hard, no timbering is required other than the stulls, which are braced from wall to wall in order to form platforms or stages to stope from. Should the reef from wall to wall prove payable, or should the vein be of a character to prohibit cleaning or sorting; and it be determined to send the whole of the stone to the, reduction works, the stuUs should be left in place until the section or block of ground is worked out, in order that if a weak spot in the walls (especially the hanging) occur, it would be possible, without any particularly extra expense or difficulty often times accompanied by danger to brace and secure the slabs. After the block became entirely stoped, it would pay where labour was cheap to remove the majority of timbers to stull another section.

Jan 1, 1901

By Parker A. J, Muir D. M

Solutions of acetonitrile in water dissolve water soluble copper(I) chloride. Removal of volatile acetonitrile from the resulting solutions, by distillation with low grade steam, precipitates pure copper(I) chloride. This is used to purify a crude copper chloride sublimate from the chlorination of nickel matte but is applicable to other sources of copper(I) chloride. The pure product can be converted to pure copper(I) oxide, copper(II) oxychloride or pure copper metal directly.

Jan 1, 1980

By D Pilone

The Tyrrhenian micro-nodules, findable at low depths (200/600 m under s l) are a reasonable reserve of manganese. They can be easily and cheaply recovered but do not contain valuable metals as in the case of oceanic nodules. In this work a hydrometallurgical process for manganese recovery from Tyrrhenian nodules is presented. The studied treatment includes the following operations: magnetic enrichment, reducing leaching, leach liquor purification and electrowinning . The study shows that the most important step in the process is the preliminary manganese enrichment. It can be done directly on the platform reducing not only the transport cost, but also the residue mud in the metallurgical plant. The leaching parameters such as status and size of nodules, temperature, composition of leaching solution and S/L ratio have been investigated. After purifying the leach liquor by iron precipitation as ammonium jarosite , the conditions to electrowin manganese have been investigated. The yields of both manganese leaching and iron precipitation together with current efficiency and specific energy consumption in the electrowinning step are given.

Jan 1, 2000

By M Maguire

The purpose of this paper is to provide an illustration of the Resource Management Act processes at their best. Many of you will be aware of the Martha Mine situated in the middle of Waihi Township in Hauraki District. Underground mining ceased on Martha Hill in the 1950s. A new mining licence was issued in the late 1980s and since that date open cast mining has continued at the site. The Hauraki District Council notified its proposed plan in October 1994. Prior to that date numerous discussion papers and draft sections of the plan had been disseminated in the community. Considerable consultation was undertaken with all interest groups. As an indication of the success of that consultation process only 17 references to the Environment Court were lodged following the making of decisions on submissions and further submissions. Those references, which included a number from the Minerals Industry, were all resolved by consent. Out of the reference and consent order process EMMA (Extended Martha Mineral Area) was born.

Jan 1, 1998