small gold flotation machine gold mining

small scale mining in south africa - jxsc machine

South Africa is endowed with large amounts of mineral wealth and is a global player with regards to the production of minerals and mineral-related products. The country is a major producer of a wide range of minerals, including precious metals, base metals, precious and semi-precious stones, and industrial minerals. Historically, this production can be attributed to large- to medium-scale mines controlled mostly by multi-national companies. Mining has contributed to the development of an extensive and efficient physical infrastructure and to the establishment of secondary industries. The historical impact of mining on the development of this country is apparent from the correlation of occurrence of high value mineral deposits and levels of development and high population densities. Past policies and discriminatory laws have resulted in lttle development of the small-scale mining subsector and hindered the participation of certain sections of the countrys population.

The definition of small-scale mining (particularly when considering artisanal mining, which is primitive and informal) has been debated at length at different fora. The most commonly used parameters for classification of the scale of a mine are gross annual turnover and number of employees. The South African Small Business Act of 1996, has classified businesses into micro, very small, small and medium according to criteria such as number of employees, total annual turnover and total assets. However, for mining thisclassification has some shortcomings. For example, on the one hand companies may be employing as few as three highly qualifed professionals as consultants and have a gross annual turnover of over 7.5 million Rand (approximately US$753,770), and on the other hand cooperative style mining operations with more than 50 people working a single deposit, using rudimentary methods, could have an annual turnover of less than R150 000 (ca. US$15,075). The majority of the group targeted by the activities of Mintek s2 Small-Scale Mining Division and other similar organizations are referred to as artisanal miners who are being supported to become true small-scale miners.

Activities are concentrated in the known mineral regions of the country, i.e., gold in the greenstone belts, diamonds where alluvial deposits exist in the Northern Cape and North West provinces. Coal mining at an artisanal level is found in KwaZulu Natal and the Eastern Cape. In the latter, the coal is used mainly for firing clay bricks. Mining methods include open pit to primitive underground excavations. Some artisanal and small-scale miners informally re-open old mine workings to access whatever ore has been left by the large mining companies. The reworking of dumps left behind by the same large mining companies is also quite common. The degree of participation of the small-scale mining subsector varies by commodity. This can be seen in the percentage employment of the subsector by commodity (see Table 2). The level of participation is determined by: availability of deposits; ease of mining, processing and extraction of the commodity; and access to markets. Some activities, such as sand and clay mining for brickmaking, are driven by local demand. These deposits fall within the soft-rock quarrying commodity group and are readily available to the small-scale miners. The minimum and uncomplicated processing requirements also make them attractive to this subsector, as reflected by the higher percentage of employees.

There are a number of pieces of legislation that impact on this group of miners and they are the same ones to which the medium and large mining companies are subject. These cover the environment; labour; mineral rights; exploration and mining permitting; and skills development. The mining policy of most countries, which is enforced by laws and legislative regulations, is usually in a language too complex for the artisanal and small-scale miners to comprehend. Most of these miners are not even aware of the national laws and regulations in force that affect the mining sector and inadvertently violate them. In South Africa the following areas are regulated: Mineral rights The issue of mineral rights in South Africa is under review. Minerals rights are like property rights and are protected by the constitution. Previously, South Africa had a dual system of private and public ownership, but the new Mineral and Petroleum Bill will make the State the sole owner of mineral rights. The issues of royalties, prospecting and mining rights also fall under this bill. Health and safety Health and safety aspects are governed by the Mine Health and Safety Act of 1996. Most of its regulations do not apply to small-scale miners. Environment management In South Africa the environmental legislation is governed by the National Environmental Management Act of 1998, the Mining and Minerals Act of 1991, environmental impact assessment (EIA) guidelines of 1997, the Environmental Conservation Act of 1 986 and the aide-memoire requirements of 1992. With the new legislation, however, all small-scale mining operations applying for prospecting or mining permits are forced to pay a deposit for environmental rehabilitation. Compliance is very low, as non-registration or illegal mining frequently occurs. Similarly, most small-scale miners have neither the resources nor the capacity to carry out an EIA. In response to these problems, the Department of Minerals and Energy (DME) has developed simplified EIA requirements, which are applied to artisanal miners defined as non-mechanized operations. Labour relations The key pieces of legislation governing labour relations in mining are the Labour Relations Act of 1995, the Basic Conditions of Employment Act of 1997, the Employment Equity Act of 1998 and the Skills Development Act of 1998. In each case, only small portions of the law are applicable to small- and artisanal mining. Skills development The Skills Development Act of 1998 sets out the frame-work for developing a coordinated approach to skills development in the country. The act was promulgated in order to improve productivity in the workplace, promote self-employment, and encourage employers to use the workplace as an active learning environment and to provide opportunities for new entrants to the labour market to gain work experience. Its regulatory impact on the artisanal and small-scale miners is also limited.

The efective participation of artisanal and small-scale miners in the sector is hampered by their lack of technical, business and management skills, and by their limited access to mineral deposits, capital and markets. Artisanal/small-scale miners are involved in almost all mineral commodities found in South Africa.

The availability of deposits and the daunting task of acquiring mineral rights limit the activities of artisanal and small-scale miners. It is often difficult to find out where mineral rights are located. Most artisanal and small-scale mining activities take place around small deposits, unsuitable for exploitation by the large mining companies. This is particularly true of deposits of precious metals and precious stones. Artisanal and small-scale miners are also often allowed to reprocess tailings dumps left behind by large mining companies. The lack of easy access to mineral deposits could be part of the underlying reasons for the existence of some of the informal artisanal mining activities.

Comparisons between different scales of production show that, although the basic industrial processes are the same, the differences in scale often necessitate application of different technologies. With increasing scale, there is a trend towards more sophisticated technologies. For the established small-scale miner, access to technology is not as much of an obstacle as it is for miners lower on the scale (i.e., artisanal). However, common throughout this subsector is the preference for generic technologies that are no longer protected by patents. Patented technologies tend to be too expensive for small-scale operators. Just as important as access to technology is the ability to use these technologies. Within the upper end of the small-scale mining sector, appropriately qualified skills may be hired. However, at the lower end this is often not feasible. The negative impacts resulting from lack of skills and limited access to technology are evident in the observed operations that are rudimentary, unsafe, environmentally unfriendly and using inefficient processes. A most horrific example of the negative impacts is misuse of mercury during gold extraction; the mercury is handled unsafely, posing a health hazard and there is no real concern for the environmental impact. Another horrific common occurrence in the small-scale mining subsector is unsafe coal and clay excavations, where the low competence of the rock makes overhangs liable to collapse, resulting in injuries and sometimes fatalities. In some SADC3 countries, the small-scale miners have been supported by free or subsidized technical and management services training, and by plant and equipment hire administered by governments. Non-governmental organizations have also been known to be instrumental in setting up central processing facilities for use by small-scale miners, e.g., the Shamva Mining Centre in Zimbabwe established by the Intermediary Technology Development Group. This provides an alternative to the somewhat unsatisfactorily custom milling and processing done by the more established small-scale mining companies for the producers at the lower end of the scale (mostly artisanal miners).

Smaller companies have different financing requirements than do larger companies, and they need support from the investment community. I ending to this sector is perceived to be risky; consequently, the domestic banks generally restrict lending to only short-term investments, if they lend at all. This greatly hampers the development of the subsector. The risk profile of a potential project is at its peak in the early stages and decreases through the development phases. Most companies never find an ore body, but a few are extremely successful. The risks at the early stages, that is, before a pre-feasibility study is completed, are normally beyond what typical commercial banks are willing to expose themselves to.

Low capitalization limits the amount of funds that small-scale miners can allocate to proper market research. At the artisanal level, the process of finding markets is unsystematic and haphazard. In some countries, where small-scale mining activities have been supported through government initiatives, the establishment by government of a central buying facility such as in Zimbabweassists the lower end of the scale. However, to more established mining companies, this set-up couldif legislated-become a hindrance to obtaining competitive prices. Some countries, for example Bolivia and Peru, have acted to close their state-controlled mining banks. Others have focused on precious metals and stones, like Vietnam, which has contracted private trading companies to buy rubies from small-scale miners with an agreement to provide training in cutting and polishing to the miners. No central buying facilities exist in South Africa, but some assistance with accessing foreign markets is available through the Department of Trade and Industry. However, most artisanal and small-scale miners are unaware of the existence of such services, and may also lack the capacity to individually attain the critical mass required by the market.

Policy-makers in South Africa recognize the need to promote the development of an efficient small-scale mining subsector. Legislation in South Africa is being adapted to play an important role in the support of artisanal and small-scale mining and will play a major role in its sustainability. The October 1998 white paper of a new minerals bill, which is currently being debated, stated thatGovernment will encourage and facilitate the sustainable development of small-scale mining in order to ensure the optimal exploitation of small mineral deposits and to enable this sector to make a positive contribution to the national, provincial and local economy. The new Minerals and Petroleum Resources Development Bill will open up the mining industry and facilitate new entries. Moreover, the Council for Geosciences is currently developing a central database of all known state owned deposits in South Africa, thus making it easier to find out where mineral rights are located. There is also a need to simplify the process of applying for mineral rights. The change in atudes has resulted in some encouraging developments, such as joint ventures between small and large mining companies. This allows access for small-scale operations to mineral deposits and sometimes guarantees markets. However, the latter has to be weighed against the same negative impacts experienced with legislated central buying systems. One example of these ventures is in the Northern Cape, where the Small Scale Miners Forum has gone into a joint venture with Samancor, which has leased them its mineral rights to some manganese deposits. Some large mining companies have allowed small-scale miners to rework their tailings or marginal areas with the understanding that all the production would be sold through the large companies. At the OKiep Mine, a group of small-scale miners have been allowed to upgrade oxide copper dumps by handpicking and selling the concentrate to the mine.

Small portable gold washing plant for sale The project on Mining, Minerals and Sustainable Development (MMSD) in Southern Africa made recommendations for the support of the small-scale mining subsector by providing appropriate training and capacity-building programmes through partnerships among government, educational institutions, companies and donors. It also recommended the creation of a regional forum to promote the development of a harmonized regional legal framework. In many countries where small-scale mining activities are present, the necessary services are made more accessible through government programmes; these may sometimes include subsidized rates. In South Africa there is a host of companies and individuals that offer services to the small-scale mining sector at normal market rates. Some of these service providers are government science councils such as Mintek, the Council for Geosciences and CSIR s Miningtek. Low capitalization of small-scale mining projects makes accessibility to overseas service providers extremely dificult. For the lower end of the small-scale miners, the National Steering Committee of Service Providers to Small- Scale Miners (NSC) was formed by the Department of Minerals and Energy to offer a more accessible service in a one-stop-shop configuration. The main motivation behind the establishment of the NSC was to correct the practices of artisanal mining especially unacceptable safety standards and environmentally unfriendly methodsby assisting this type of operation to advance to the higher level of small-scale mining and ensure sustainability. The services of the NSC are also extended to: First-time entrepreneurs with limited experience and expertise and who are trying to enter the mining sector by starting green-field operations; Formal small- or medium-sized operations that are operating below the potential of the deposit being exploited, due to lack of expertise and expansion capital. The NSC includes specialists in geological prospecting, mining, minerals processing, diamond recovery, capacity building and manufacturing. The Committee represents the following organizations: Mintek, Miningtek, the Council for Geosciences, Ntsika, the Industrial Development Council (IDC) and Khula. The NSC also gives financial support through IDC and Khula. Other finance institutions involved or having an interest in the small-scale end of the mining sector include the New Africa Mining Fund7 and the International Finance Corporation (IFC). These institutions are involved, or wish to be more involved, in the sector as they believe that the small-scale mining sector is a potential growth area, particularly in light of the new minerals bill. The investors in the New Africa Mining Fund (NAMF) will include South African financial institutions, mining houses and development finance institutions. It is expected that NAMF will invest in smaller mining ventures and promote junior mining activities. The Fund is supposed to invest at the pre- feasibility, feasibility and early production stages of smaller mining projects. Funding will be approved according to criteria that include: The viability of the project; The composition of the promoting agent; Black economic empowerment criteria.

The Skills Development Act of 1998 is being enforced through the setting up of a National Skills Authority, imposing a skills- development levy on employers, setting up a National Skills Fund, developing labour centres and setting up a skills development planning unit. In the mining sector, the Skills Development Act is implemented through the Mining Qualifications Authority. This body is responsible for the development of unit standards, national and accrediting qualifications, and of training providers in the sector. Several groups have been formed to generate standards and qualifications to cover the different areas of the mining sector, one of which specializes in the small-scale mining subsector. The skills requirements for artisanal and small-scale miners are covered by the following broad areas: Geology; Mining; Mineral processing; Environment; Health and safety; Operational management; Marketing; Financial management; Human resources management; Business planning.

The small-scale mining subsector has great potential for growth. This potential can be realized through coordinated activities, such as those of the NSC, and as part of the integrated rural development plans for local government. The underlying ethos in all the initiatives is the drive towards sustainable development through beneficiation, downstream processing and adding value. Minteks intervention strategies to support artisanal and small-scale miners include: Beneficiation and value-addition development programmes for poverty alleviation focused on the rural development nodes of South Africa; Development/application of appropriate and safer technologies; Facilitation of technology transfer through training; Provision of entrepreneurial skills and access to technology, mineral deposits and financial resources.

gold flotation

Though the gold recovery methods previously discussed usually catch the coarser particles of sulphides in the ore and thus indirectly recover some of the gold associated with these and other heavy minerals, they are not primarily designed for sulphide recovery. Where a high sulphide recovery is demanded, flotation methods are now in general use, but in the days before flotation was known, a large part of the worlds gold was recovered by concentrating the gold-bearing sulphides on tables and smelting or regrinding and amalgamating the product.Though the modern trend is away from the use of tables, because flotation is so much more efficient.

The flotation process, which is today so extensively used for the concentration of base-metal sulphide ores and is finding increased use in many other fields. In1932flotation plants began to be installed for the treatment of gold and silver ores as a substitute for or in conjunction with cyanidation.

The principles involved and the rather elaborate physicochemical theories advanced to account for the selective separations obtained are beyond the scope of this book. Suffice it to say that in general the sulphides are air-filmed and ufloated to be removed as a froth from the surface of the pulp while the nonsulphide gangue remains in suspension, or sinks, as the expression is, for discharge from the side or end of the machine.

For more complete information reference is made to Taggarts Hand book of Mineral Dressing, 1945; Gaudins Flotation and Principles of Mineral Dressing; I. W. Warks Principles of Flotation; and the numerous papers on the subject published by the A.I.M.E. and U.S. Bureau of Mines.

Flotation machines can be classed roughly into mechanical and pneumatic types. The first employ mechanically operated impellers or rotorsfor agitating and aerating the pulps, with or without a supplementary compressed-air supply. Best known of these are the Mineral Separation, the Fagergren, the Agitair, and the Massco-Fahrenwald.

Pneumatic cells use no mechanical agitation (except the Macintosh, now obsolete) and depend on compressed air to supply the bubble structure and tohold the pulp in suspension. Well-known makes include theCallow and MacIntosh (no longer manufactured) the Southwestern, and the Steffensen, the last, as shown in the cross-sectional view in Fig. 47, utilizing the air-lift principle, with the shearing of large bubbles as the air is forced from a central perforated bell through a series of diffuser plates.

The number and size of flotation cells required for any given installation are readily determinedif the problem is looked upon as a matter of retention time for a certain total volume of pulp. The pulp flow in cubic feet per minute is determined from the formula

For ordinary ratios of concentration the effect on cell capacity of concentrate (or froth) removal can be neglected, but where a high proportion of the feed is taken off as concentrates, or where middlings are removed for retreatment in a separate circuit, due allowance should be made for reduced flow and, in consequence, increased detention time toward the tail end of a string of cells. Not less than a series of four cells and preferably six or more cells should be used in any roughing section in order to prevent short-circuiting.

It is not intended here to discuss the subject of flotation reagents in anydetail. The subject is a large one with a comprehensive technical and patent literature. Research leading to the development of new reagents and to our understanding of the mechanism involved has been largely in the hands of academic institutions and the manufacturers of chemical products.

Recent work reported by A. M. Gaudin on the use of Radioactive Tracers in Milling Research described, for instance, the use of a flotation reagents containing radioactive carbon to determine the extent of collector adsorption. The bubble machine devised to measure the angle of contact of air bubbles on collector-treated mineral surfaces has been extensively used for determining the theoretical value of various reagents as flotation collectors, but for the most part the actual reagent combination in use in commercial plants is usually the result of trial-and-error methods.

The following is a brief discussion of the reagents ordinarily used for the flotation of gold and silver ores prepared from notes submitted by S. J. Swainson and N. Hedley of the American Cyanamid Company.

Conditioning agents are commonly used, especially when the ores are partly oxidized. Soda ash is the most widely used regulator of alkalinity. Lime should not be used because it is a depressor of free gold and inhibits pyrite flotation. Sodium sulphide is often helpful in the flotation of partly oxidized sulphides but must be used with caution because of its depressing action on free gold. Copper sulphate is frequently helpful in accelerating the flotation of pyrite and arsenopyrite. In rare instances sulphuric acid may be necessary, but the use of it is limited to ores containing no lime. Ammo-phos, a crude monoammonium phosphate, is sometimes used in the flotation of oxidized gold ores. It has the effect of flocculating iron oxide slime, thus improving the grade of concentrate. Sodium silicate, a dispersing agent, is also useful for overcoming gangue-slime interference.

Promoters or Collectors. The commonly used promoters or collectors are Aerofloat reagents and the xanthates. The most effective promoter of free gold is Aerofloat flotation reagent 208. When auriferous pyrite is present, this reagent and reagent 301 constitute the most effective promoter combination. The latter is a higher xanthate which is a strong and non-selective promoter of all sulphides. Amyl and butyl xanthates are also widely used. Ethyl xanthate is not so commonly used as the higher xanthates for this type of flotation.

The liquid flotation reagents such as Aerofloat 15, 25, and 31 are commonly used in conjunction with the xanthates. These reagents possess both promoter and frother properties. When malachite and azurite are present, reagent 425 is often a useful promoter. This reagent was developed especially for the flotation of oxidized copper ores.

The amount of these promoters varies considerably. If the ore is partly oxidized, it may be necessary to use as much as 0.30 to 0.40 lb. of promoter perton of ore. In the case of clean ores, as little as 0.05 lb. may be enough. The promoter requirement of an average ore will usually approximate 0.20 lb.

The commonly used frothers are steam-distilled pine oil, cresylic acid, and higher alcohols. The third mentioned, known as duPont frothers, have recently come into use. They produce a somewhat more tender and evanescent froth than pine oil or cresylic acid; consequently they have less tendency to float gangue, particularly in circuits alkaline with lime. The duPont frothers are highly active frothing agents; therefore it is rarely necessary to use more than a few hundredths of a pound per ton of ore.

When coarse sulphides and moderately coarse gold (65 mesh) must be floated, froth modifiers such as Barrett Nos. 4 and 634, of hardwood creosote, are usually necessary. The function of these so-called froth modifiers is to give more stable froth having greater carrying power.

The conditioning agents used for silver ores are the same as those for gold ores. Soda ash is a commonly used pH regulator. It aids the flotation of galena and silver sulphides. When the silver and lead minerals are in the oxidized state, sodium sulphide is helpful, but it should not be added until after the sulphide minerals have been floated, because sodium sulphide inhibits flotation of the silver sulphide minerals.

Aerofloat 25 and 31 are effective promoters for silver sulphides, sulphantimonites, and sulpharsenites, as well as for native silver. When galena is present, No. 31 is preferable to No. 25 because it is a more powerful galena promoter. Higher xanthates, such as American Cyanamid reagent 301 and amyl and butyl xanthates, are beneficial when pyrite must be recovered. When the ore contains oxidized lead minerals, such as angle-site and cerussite, sodium sulphide and one of the higher xanthates may be used. In some instances reagent 404 effects high recovery of these minerals without the use of a sulphidizing agent.Silver ores require the same frothers as gold oresviz., pine oil, cresylic acid or duPont frothers.

Aero, Ammo-phos, and Aerofloat are registered trade-marks applied to products manufactured by this company. The Great Western Electro-Chemical Company, California, makes amyl xanthate, butyl xanthate, potassium xanthate, and sodium xanthate. In the United States these reagents are used on the gold ores of California and Colorado and in Canada on the gold ores and sulphides of Ontario and Quebec.

Flotation reagents of the Naval Stores Division of the Hercules Powder Company are as follows: Yarmor F pine oil, a frother for floating simple and complex ores; Risor pine oil, for recovering sulphides by bulk flotation; Tarol a toughener of froth, generally used in small amount with Yarmor F, but with some semioxidized ores where high recovery is essential yet the grade of concentrate not so important, Tarol does good work; Tarol a frother for floating certain oxide minerals, but it can be used in selective flotation of sulphide minerals and in bulk flotation where tough frothis desirable; Solvenol, for the floating of graphite in conjunction with Yarmor F.

The statement has come to the attention of the American Cyanamid Company that organic flotation reagents, such as xanthates, even in the small amounts used in flotation, cause reprecipitation of gold from pregnant cyanide solutions. The ore-dressing laboratory of this company is studying the question, and preliminary results indicate that this statement is unfounded. The addition of xanthate, in the amount usually found in flotation circuits, does not precipitate gold from a pregnant cyanide solution containing the normal amount of cyanide and lime.

Valueless slime, in addition to its detrimental effect in coating gold-bearing sulphide, thereby limiting or preventing its flotation, also becomes mixed with the flotation concentrate and lowers its value. Sometimes the problem in flotation is that, although the gold is floatable, the concentrate product is of too low grade. Talc, slate, clay, oxides of iron, and manganese or carbonaceousmatter in ores early form slime in a mill, without fine crushing. Such primary slime, according to E. S. Leaver and J. A. Woolf of the U.S. Bureau of Mines, interferes with the proper selectivity of the associated minerals and causes slime interference. The tendency of primary slime is to float readily or to remain in suspension and be carried over into the concentrate. Preliminary removal and washing of this primary slime before fine crushing is one method of dealing with it. At the Idaho-Maryland mill, Grass Valley, Calif., starch is regularly used as a depressant during flotation. Flotation tests using starch were made on a quartz ore containing carbonaceous schist from the Argonaut mine, Jackson, Calif.; a talcose ore from the Idaho-Maryland mine mentioned; a talcose-clayey ore from Gold Range, Nev.; a siliceous, iron and manganese oxide ore from the Baboquivari district, Nevada; carbonaceous and aluminous slime from the Mother Lode and some synthetic ores. The conclusions from the foregoing tests were in part as follows:

It acts first on the slime; then, if a sufficient excess of starch is present, it will cause some depression of sulphides and metallic gold, either by wetting out or by producing an extremely brittle froth. Therefore, care must be taken in regulating the amount of starch added to obtain the maximum depression of the slime commensurate with high recovery of the gold. In this, as in all other phases of flotation, each ore presents an individual problem and must be so studied.

It wasdescribe by the use of 600 series of flotation reagents which were developed primarily for the purpose of depressing carbonaceous and siliceous slimes in the flotation of gold ores. Carbonaceous material not only greatly increases the bulk and moisture content of a flotation concentrate, but its presence makes cyanidation of the concentrate difficult or impossible owing to reprecipitation of the gold during treatment.

In the treatment of an auriferous sulphide ore associated with carbonaceous shale from South Africa, up to 77 per cent of the carbon was eliminated by the use of 1 lb. per ton of reagent 637 with a 90.5 per cent gold recovery at 20.4:1 ratio of concentration.

A gold carbonaceous sulphide ore from California carrying free gold yielded a 93 per cent recovery into a concentrate at 14.4:1 to ratio of concentration after conditioning with 0.50 lb. per ton of reagent 645.

In each case the ore was ground to about 70 per cent minus 200 mesh and conditioned at 22 per cent solids with the reagents as indicated. Flotation reagents included reagents 301 and 208 and pine oil. In the second case some soda ash and copper sulphate where also used.

It is obvious that the most suitable treatment for ores carrying gold and silver associated with pyrite and other iron sulphides, arsenopyrite or stibnite, will depend on the type of association. Cyanidation is usually the most suitable process, but it often necessitates grinding ore to a fine size to release the gold and silver. Where it is possible to obtain a good recovery by flotation in a concentrate carrying most of the pyrite or other sulphides, it is often more economical to adopt this method, regrinding only the comparatively small bulk of concentrate prior to the leaching operation.

That the trend over the last 10 years has been in this direction will be noted from the numerous examples of such flow sheets in Canada and Australia (see Chap. XV). A number of plants formerly using all-cyanidation have converted to the combined process.

The suitability of the method involving fine grinding and flotation with treatment of the concentrate and rejection of the remainder should receive careful study in the laboratory and in a pilot plant. Mclntyre-Porcupine ran a 150-ton plant for a year before deciding to build its 2400-ton mill. Comparative figures given by J. J. Denny in E. and M. J., November, 1933, on the results obtained by the all-sliming, C.C.D. process formerly used and the later combination of flotation and concentrate treatment showed a saving of 12.1 cents per ton in treatment cost and a decrease of 15 cents per ton in the residue, a total of 27.1 cents per ton in favor of the new treatment.

Flotation may also prove to be the more economical process for the ore containing such minerals as stibnite, copper-bearing sulphides, tellurides,and others which require roasting before cyanidation, because this reduces the tonnage passing through the furnace.

Even when recovery of gold and silver from such ores by flotation is low, it may be advantageous still to float off the minerals that interfere with cyanidation, roasting, and leaching or possibly to smelt the concentrate for extraction of its precious metals. Cyanidation of the flotation tailing follows, this being simpler and cheaper because of prior removal of the cyanicides.

It is a good practice to recover as much of the gold and silver as possible in the grinding circuit by amalgamation, corduroy strakes, or other gravity means to prevent their accumulation in the classifier; otherwise gold that is too coarse to float may escape from the grinding section into the flotation circuit where it will pass into the tailing and be lost.

To prevent this, several companies including the Mclntyre-Porcupine at Timmins, Ontario, have inserted a combination of flotation cell and hydraulic cone in their tube-mill classifier circuits. At the Mclntyre- Porcupine, according to J. J. Denny in E. and M. J., November, 1933, this cell is a 500 Sub-A type. The total pulp discharged from each tube mill passes through 4-meshscreens which are attached to the end of the mills. The undersize goes to the flotation cell, and the oversize to the classifiers. Tailing from the cell flows to the classifiers, and the flotation concentrate joins the concentrate stream from .the main flotation circuit. The purpose of the hydraulic attachment is to remove gold that is too coarse to float, thus avoiding an accumulation in the tube-mill circuit. The cones have increased recovery from 60 to 75 per cent. Every 24 hr. the tube-mill discharge is diverted to the classifiers. Water is added for 15 min. to separate the gangue in the cells from the high-grade concentrate, after which a product consisting of sulphides and coarse gold is removed through a 4-in. plug valve equipped with a locking device. Each day approximately 400 lb. of material worth $2000 to $3000 is recovered. This is transferred to a tube mill in the cyanide circuit,with no evident increase in the value of the cyanide residue. The object of this arrangement is, of course, primarily to deplete the circulating load of an accumulation of free gold and heavy sulphides.

Flotation is used to recover residual gold-bearing sulphides and tellurides. The Lake Shore mill retreatment plant is an interesting example of this technique. The problem here was, of course, to overcome by chemical treatment the depressing action of the alkaline cyanide circuit on the sulphides. A full discussion of this and of the somewhat controversial subject as to whether flotation should in such an instance be carried out before, or after cyanidation will be found in J. E. Williamsons paper Roasting and Flotation Practice in the Lake Shore Mines Sulphide Treatment Plant elsewhere referred to. Summing up the specific considerations governing the choice oftreatment, the author says:

Incidental matters that influenced the choice of treatment scheme included the realization that preliminary flotation would have involved two separate treatment circuits with additional steps of thickening and filtration following the flotation. Furthermore, in the conditioning method evolved, as much as 60 per cent of the dissolved values in the cyanide tailings were precipitated and recovered.

There are, however, cases where flotation equipment was put in for the purpose of recovering the gold in a concentrate and rejecting the tailing only to find that the tailing was too valuable to waste and had finally to be cyanided before discarding.

It is generally true that cyanidation is capable of producing a tailing of lower gold content than flotation. At a price of $35 per ounce for gold this fact is of much greater importance than when gold was valued at $20.67 per ounce. The possible gold loss in the residue to be discarded will influence the choice of a method of treatment.

flotation machine for mineral & metallurgy - jxsc machine

Application copper sulfide, gold sulfide, zinc, lead, nickel, antimony, fluorite, tungsten, and other non-ferrous metals, and also be used for coarse selection for ferrous metals and nonmetals. Type Agitating flotation machine, Self-priming, aeration flotation, flotation column. ModelXJK, SF, GF, CHF, XJC, etc. Contact us for specific & quick selection.

Flotation machine (floatation machine, planktonic concentrator) in the mineral processing plant, mainly used for separating copper, zinc, lead, nickel, gold, and other non-ferrous metal. TypeXJK series agitation impeller flotation machine (Seldom used, small capacity); SF flotation machine (Larger volume, better flotation effect); Pneumatic flotation machine (aeration and agitation, high capacity). Corollary equipmentIn front: one or two sets of mixing tank for flotation agent agitation and slurry pulp agitation. Behind: concentrate pond, thickener or filter Flotation cell According to the ore grade, mineral type and processing capacity to choose, determine the number of the flotation cells. It is recommended that carrying out the mineral flotation tests to obtain the best procedure plan, like pulp density, time, reagent selection, etc. Flotation reagentfoaming agent, collecting agent, activating agent, inhibitor, etc. BrandsWemco flotation unit, Fahrenwald Denver, Callow, BGRIMM, etc. How to select mining flotation machine1. According to the nature of the ore (washability, feed particle-size, density, grade, pulp, pH, etc.) and flotation plant scale choose the appropriate flotation machine. 2. The concentration operation is mainly to improve the ore concentrate grade. The flotation foam layer should be thin so that separates the gangue. It is not appropriate to use a flotation machine with a large aeration volume. Therefore, there are differences between the froth flotation machine of concentration, roughing and scavenging. 3. JXSC engineer team here to help do flotation mining machine selection, price inquiry, flowsheet design.

Flotation machine structureThe metallurgist flotation mainly made up of slurry tank, mixing device, aeration device, mineralized bubble discharging device and motor. Flotation machine working principleFlotation process refers to the flotation separation in mineral processing. In the flotation machine, the ore slurry treated with the added agent, by aeration and stir, some of the ore particles are selectively fixed on the air bubbles and floats to the surface of the slurry and is scraped out. The rest is retained in the pulp, thus achieve the purpose of separating different minerals. The complete froth flotation process in metallurgy consists of rougher flotation, concentrate flotation and scavenging flotation. Flotation methodFroth flotation of sulphide ores, mainly have differential flotation and bulk flotation process, improve the flotation recovery rate of fine - particle. Flotation cell manufacturerJXSC specializes in the production of a full set of mineral processing equipment, and cooperates with the Mining Research Institute to design a scientific and reliable mineral processing flowsheet, supply gold flotation, copper flotation, zinc flotation, and the like ore flotation units.

gold flotation | gold mining process | gold mining equipment for sale

Mining Equipment Manufacturers, Our Main Products: Gold Trommel, Gold Wash Plant, Dense Media Separation System, CIP, CIL, Ball Mill, Trommel Scrubber, Shaker Table, Jig Concentrator, Spiral Separator, Slurry Pump, Trommel Screen.

mining equipment manufacturer | mining machine supplier - jxsc

JXSC Mining works on offering services for the mines and mineral processing plants, escorting efficient and safe processing performance in the global mineral resources industry with our reliable mining equipment and innovative solutions. From its tough beginning, the business that started in 1985 went to win the trust both home and board, with mineral processing machines sold to over 100 countries and regions( such as USA, Canada, Australia, South Korea, Japan, Mexico, Chile, Congo, South Africa). Visit customer success cases to see what changes will our help of experience and technical expertise bring. May our experience in the various minerals like gold, silver, diamond, copper, tin, coltan, iron, chrome, titanium, etc. do you a favor in the increasing profit and reducing risks.

Overview The beneficiation processing of molybdenum ore is mainly performed by flotation, and the recovered molybdenum mineral is molybdenite(MoS2). Sometimes in order to improve the quality of molybdenum concentrate and remove impurities, the concentrated molybdenite would be subjected to a further step of chemical beneficiation processing. Introduction of molybdenite Molybedenites chemical composition with a high Read more

Due to the outbeark of Coronavirus, China have to stopped its Economy to tackle Coronavirus. Now the World Suffers. The virtual shutdown of one of the worlds biggest economies since last months is hurting business around the globe, from multinational companies to street vendor and tour guides. also, as well as the mining industry. Nowaday, Read more

The mining and metals industry is recovering from the most challenging period in decades. Market fluctuations and declining commodity prices have become a new normal. In this case, cutting costs, automating, and improving operational efficiency are critical. At the same time, industry-specific issues related to regulation, geopolitical risks, legal restrictions on the use of natural Read more

Introduction Minerals are mostly substances formed naturally in the Earth. They have a definite chemical composition and structure. Overall there are over 3000 minerals we knowns nowadays, and some are rare and precious such as gold and diamond(actually diamonds are likely the most common gem in nature), while others are more ordinary, such as quartz. Read more

What is a crusher? A crusher is a machine that is designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size of materials, or change the form of waste materials so they can be more easily disposed of or recycled, or to reduce the size Read more

Description Amphibolite is a dark, heavy, metamorphic rock composed mostly of the mineral amphibole. Amphibolites have very little to no quartz. Amphibole refers not to a single mineral, but a group of minerals. Most belong to the monoclinic crystal system, but some belong to the orthorhombic crystal system. They are silicate minerals containing SiO4 molecules. Read more

Mining Equipment Manufacturers, Our Main Products: Gold Trommel, Gold Wash Plant, Dense Media Separation System, CIP, CIL, Ball Mill, Trommel Scrubber, Shaker Table, Jig Concentrator, Spiral Separator, Slurry Pump, Trommel Screen.

gold processing plants & complete ore process plant

The chart/table below are crude budgetary estimations for the cost of major plant equipment. Actual cost will vary depending of the process details and detailed equipment list and origin. Please use this to decide if your project and dream for becoming a miner or mining company is something you can afford.