Typical Market Specifications

Tantalite on the international market generally contains a minimum of 30% Ta2O5, while lower grade material with a minimum of 20% Ta2O5 may also be of interest. The payable value is based on the Ta2O5 content alone, any Nb2O5 is generally ignored.

Should material contain mainly Nb2O5 and only little Ta2O5, then it would be sold as columbite and should contain a minimum of 50% Nb2O5. The payable value is based on the Nb2O5+Ta2O5 content payable entirely as Nb2O5; the Ta2O5 content is not paid a higher rate.

Other Requirements

The tantalum and niobium minerals often contain somewhat elevated levels of naturally occurring thorium and uranium, usually high enough for them to be classified as radioactive for handling and transport. It is incumbent on any producer or trader to also analyse for Th and U in order to demonstrate whether the material is radioactive or not. As a guide, these elements are of concern for the purpose of mining and handling at levels above 1 Bq/g, a level obtained from e.g. 0.013% ThO2 plus 0.0048% U3O8, whereas for transport the levels of concern are an order of magnitude higher, i.e. 10 Bq/g or 0.13% ThO2 plus 0.048% U3O8.

Valuation Basis

The Zenith as an international association is not allowed to gather data on nor discuss prices, forecasting or future trends, as this would be against our Charter and against anti-trust and competition laws.

It is important to understand that there are no official or published prices for tantalum or niobium minerals, as these metals are not traded on any metal exchange (London Metal Exchange or other). The price is determined solely by negotiation between buyer and seller.

Some price data may be found in the metals press or elsewhere on the Internet; care should be taken as these are generally anecdotal, are not based on collected statistics and may only reflect the views of one person who has spoken to a journalist. Examples of the metals press include Asian Metal, Metal Pages, Platts, Roskill and Ryan’s Notes, which regularly publish subscription-based information on market prices. Their web addresses are:

The following method for recovering gold from black sands comes from a combination of information found in Gold Mining in the 1990′s by Dave McCracken and How and Where to Find Gold by Verne H. Ballantyne. Both of these books can be order from Barnes and Noble by clicking on the book title.

To recover gold from black sands it is recommended that the recreational prospector only use mechanical separation. Mechanical separation is simply removing the gold from the surrounding materials by using a mechanical approach. This starts out simply by using tweezers to remove the small nuggets and flakes that are easily discernable. Following the removal of the coarse gold, the concentrate should be dried. Drying of black sands should always be done in a well ventilated area with you upwind. During the drying process, it is possible that hazardous vapors could form from natural minerals. It is always better to be safe than sorry.

Following drying, pass the sand through a screen such as window screen. Take the oversize material (particels still on the screen) and pour it on a piece of clean paper. Spread the material out and separate the gold. Sweep the unwanted material off the paper. Then transfer the gold to a storage bottle.

The undersized material from the first screen is then passed through a finer screen such as a tea strainer. The oversized particles are then placed on another clean piece of paper. Again, separate the gold from the surrounding material. This can be accomplished in several ways, including lightly blowing across the sands while holding down the piece of paper. You can also use a small painter’s brush or simply your fingers. Once there is only gold on the paper, transfer to a storage bottle.

The finally undersized material consists of small particles. Spread these particles over another clean piece of paper. Take a magnet wrapped in plastic like cling-wrap and touch the particles. Magnetic particles like magnetite will attached themselves to the magnet. Take the magnet to another clean paper and remove the platic wrap and allow the particles to fall on to the paper. Examine the particles visually and maybe pickup with the magnet wrapped again to insure no gold particles got carried away with the magneted particles.

The remaining particles on the original paper will be fine gold and non-magnetic black sands. Again, the gold can be separated from the black sands by lightly blowing across the paper. Spearation can be encouraged by lightly tapping or vibrating the paper and insuring that only a little concentrate is present on the paper. The remaining fine gold can be placed in a storage bottle.

Other methods exist that will actually recover more gold, but they involve poisonous and/or deadly chemicals. One such method,which has been widely used in the past, involves the cleaning the concentrate with nitric acid then recovering gold by amalgamation with mercury. Nitric acid are dangerous and mercury is poisonous. Another method uses cyanide to dissolve gold into a solution with a pH greater than 10. The gold can then be cemented out of solution by adding zinc powder (The Merrle-Crowe Process). The resulting powder after throughly rinsing can be melted. The zinc will float on top of the gold and can be skimmed off. If the pH of the dissolution solution is not controlled, hydrogen cyanide can form if the pH becomes to low. Hydrogen cyanide is what is used in gas chambers. Finally, I have seen offers by companies claiming to provide environmentally safe recover methods. There are technically viable chemical processing routes using halides, thiourea and/or thiosulfate that would fit these descriptions. Unfortunately, the cost to run these systems may not be worth the amount of gold recovered. The reader is left to make his/her own decision concerning cost versus benefit of such systems.

Here is another method that was submitted to me by CoalBunny. Thanks for the submission! “There is another technique for dealing with black sands. White vinegar and table salt. Acetic acid+sodium chloride=sodium acetate (liquid) and chlorine (gas). The chlorine that is released in a quantity that it’s essentially harmless if at all noticable. The sodium acetate removes the gangue films from the gold. You will find in many locations that the presence of Hg is blamed on the mining community. In the majority of locations this is not as true as the environmental community wishes as it is a natural occurance. I think you know what goes on from there- Gold attracts the mercury, mercury then attracts a myraid of metals that also occur in the area, and they oxidize. End result is gold that doesn’t look like gold. Treat it with the vinegar and salt and it’ll remove the tarnish and the gold with most likely by silver from the Hg. Heat it or treat it with nitric and you have the gold. I prefer the nitric as you can recover the Hg from it.”

The planning of a completely new plant for the aggregate, cement, lime and gypsum industries is taken care of by long-serving specialists. They lay down the required process techniques, design and manufacture the machinery and components and then install, erect and commission the complete plant.

That’s the reason why stationary plants from Benco bring a maximum of performance and return with a minimum of maintenance and operating costs.

In addition to that Benco offers one of the widest ranges of strong, robust and proven machines and components, such as gyratory crushers, Kubria® cone crushers, hammer crushers, impact crushers, single- and doubletoggle jaw crushers, roll crushers, scalpers, screens, vibrating feeders etc.

Greenstone processing plant equipped with a hydraulic reciprocating plate feeder, Turbo screens and two Kubria® cone crushers at Burgk in Germany.

Gravel processing and loading plant with a maximum processing and loading capacity of 900 t/h installed at Hülskens Liebersee GmbH & Co. KG in Germany. View of a part of the processing plant with screens, fluidized bed separator and bucket wheel.

Stationary secondary crushing plant equipped with an impact crusher at Loma Negra S.A., Olavarria, Argentina. Capacity: 900 t/h of limestone producing a final grain size of 0-19 mm.

Stationary two-stage plant with double-roll crushers at the Märker Cement Works in Germany. Capacity: 1000 t/h of limestone producing a final grain size of 0-80 mm.

A limestone processing plant at Alfred Moeck KG in Lenningen, Germany with a capacity of 1000 t/h. The plant produces mineral product sizes of 0-56 mm using a jaw-type gyratory crusher, a reciprocating plate feeder, screens with double out-of-balance drive, fines screens and Kubria® cone crushers.

Pulverized minerals are produced at specialized processing plants. These plants supply mineral products ranging from sizes of approximately 1 micrometer to more than 75 micrometers aerodynamic diameter. Pharmaceutical, paint, plastics, pigment, rubber, and chemical industries use these products. Due to the specialized characteristics of the mineral products and the markets for these products, pulverized mineral processing plants have production rates that are less than 5% of the production capacities of conventional crushed stone plants. Two alternative processing systems for pulverized minerals are summarized in Figure.

In dry processing systems, the mineral aggregate material from conventional crushing and screening operations is subject to coarse and fine grinding primarily in roller mills and/or ball mills to reduce the material to the necessary product size range. A classifier is used to size the ground material and return oversized material that can be pulverized using either wet or dry processes. The classifier can either be associated with the grinding operation, or it can be a standalone process unit. Fabric filters control particulate matter emissions from the grinding operation and the classifier. The products are stored in silos and are shipped by truck or in bags. In wet processing systems, the mineral aggregate material is processed in wet mode coarse and fine grinding operations. Beneficiation processes use flotation to separate mineral impurities. Finely ground material is concentrated and flash dried. Fabric filters are used to control particulate matter emissions from the flash dryer. The product is then stored in silos, bagged, and shipped.

The chemical formula of sphalerite ZnS, the crystal structure of equiaxed zinc ion is located in the center of the unit cell of the horns and all surface. S is located in the center of the four small cubes in the unit cell are divided into eight small cubes. Concentration of potassium permanganate for 4 ~ 6 × 10-5 mol / l strongly inhibited the activation of sphalerite at high concentration the Shique so good zooplankton. Its mechanism of action is: the low concentration of potassium permanganate with sphalerite surface activation of the membrane surface lattice ions by the reaction of metal hydroxy compounds from the inhibition and xanthate desorption at high concentrations in the mineral surface redox the reaction of elemental sulfur.

Cyanide strongly inhibited the sphalerite, in addition to zinc sulfate, thiosulfate and so can inhibit the flotation of sphalerite.

Pyrite is the most widely distributed sulfide in the earth’s crust, formed in various geological conditions, symbiotic with other minerals. Pyrite can exist in a variety of stable field is larger crystal field stabilization energy and additional adsorption energy because the electron configuration of Fe2 + to make it into the composition of the sulfide ion in the octahedral field. Therefore, pyrite can be formed and stabilized in a variety of geological conditions.

In addition to the pyrite crystal structure, chemical composition, surface structure to Flotability influential, many studies show that pyrite metallogenic conditions of ore formation characteristics, texture and structure of the ore and other factors also have an impact. Stone through the original thirteen deposit pyrite chemical analysis results indicate that the ore samples of the S / Fe ratio fluctuations are mostly in the range of 1.93 to 2.06 S / Fe ratio closer the theoretical value of 2, yellow iron The mine Flotability better. Chen Shuwen on eight different origin of the pyrite flotability study that pure iron sulfur than to determine its Flotability has some limitations, pyrite floatability of its semiconductor nature and chemical composition. The relationship between the two: the S / Fe is high pyrite N-type semiconductor, the thermoelectric power is negative, poor Flotability, easily Na2S,, Ca 2 + ion suppression; the S / Fe ratio close to the theoretical value of 2 who can be both P-type N-type semiconductor in acidic medium may be floating in an alkaline medium Flotability; the S / Fe ratio of low pyrite for the P-type semiconductor, the thermoelectric power in alkaline medium Flotability difficult Na2S, of Ca2 + suppression, but in acidic medium may be floating.

The short chain xanthate traditional flotation of pyrite, the hydrophobic product dixanthogen. Xanthate and pyrite at pH less than 6 in acidic media easy to float, but the pH of 6 to 7 different studies have shown that its floating worse or better floating. Ling Jinghong studies suggest that this phenomenon is the ore sample handling. Under alkaline conditions, the pyrite floatability decreased with increasing pH value.

Activator of pyrite generally used sulfuric acid, the addition can also be used Na2CO3 or CO2 activation. The mechanism of action as follows: One is to lower the pH value, the pyrite surface of Ca2 +, Fe2 + and Fe3 + ions to form complexes or insoluble salts into the solution, to restore the fresh surface of the pyrite from the pyrite surface desorption; The second is to be activated due to the presence of the activator of the pyrite surface is difficult to be oxidized, which was inhibited pyrite float. When the surface oxidation of pyrite deeper, Cu2 + activation. Fe2 + in the mechanism of Cu2 + can replace the pyrite lattice, so that the surface of the copper sulfide film thereby enhancing the adsorption of xanthate; but pyrite adsorption flotation or by lime inhibition deeper, you need to acidic medium or CuSO4 activated only after acid cleaning.

3.2 Lead and Zinc Flotation

Commonly used in flotation of lead-zinc deposit:

Xanthate class such preparations, including xanthate, xanthate ester.

Two. Sulfur and classes, such as diethyldithiocarbamate, its ability to collectors than xanthate strong. Collector capacity of galena, chalcopyrite, pyrite collectors school weak selective flotation faster, uses less than xanthate. Strong collector for Copper, Lead and sulfur than the ore sorting, separating effect can be better than the xanthate on the sulfide ore coarse living body.

3. Black drug class

Black drug sulfide ore flotation, and its ability to collectors than xanthate weak solubility product of the same metal ion dialkyl dithio phosphate compared with the corresponding ions xanthate. Black medicine foaming properties.

Commonly used in industry aerofloat: No. 25 black drug, the small the ammonium black medicine amine aerofloat, naphthenic aerofloat. Small the ammonium black drug (dibutyl dithiophosphate ammonium phosphate) as a white powder, soluble in water, deliquescence after dark, a certain foaming properties, such as copper, lead, zinc, nickel sulfide ore flotation . Weak weak alkaline pulp collector on pyrite and pyrrhotite, galena collector ability.

3.3 lead and zinc flotation adjusting agent

Adjust the dose according to their role in the flotation process can be divided into: the inhibitor, activator, medium pH adjusting agent, slime dispersants, coagulants and continued coagulant.

Control agents include a variety of inorganic compounds (such as salt, alkali and acid), organic compounds. With a pharmaceutical under different flotation conditions often play a different role.

1, inhibitor

A. Gray limestone (CaO) have a strong water absorption and hydrated lime Ca (OH) 2 reacts with water. It is insoluble in water, is a strong base to join in the flotation pulp reaction is as follows:

CaO + H2O = Ca (OH) 2

Ca (OH) 2 = CaOH + + OH-

CaOH + = Ca2 + +0 H-

Lime is commonly used to improve slurry PH value, inhibition of iron sulfide minerals. Frequently in the copper sulfide, lead, zinc ore, pyrite (pyrite, pyrrhotite, and marcasite, sulfur and arsenic in iron ore (eg, arsenopyrite) for more benefits of flotation copper, lead, zinc minerals, often need to add lime to inhibit iron sulfide minerals.

Lime, galena, especially the surface is slightly oxidized galena, inhibition. Therefore, the flotation of galena from the polymetallic sulfide ore, often with sodium carbonate to adjust the slurry pH. Due to high content of pyrite, with lime to adjust pulp pH should pay attention to controlling the amount of lime.

Lime affect the foaming agent, foaming ability, such as loose drunk oil from the gown foaming ability of the agent increases with the rise of PH, phenolic foaming agent, foaming ability increased with pH reduced.

Lime is a coagulant make mine oars in the fine particles condensation. Thus, when the lime with the optimum at that time, froth can maintain a certain degree of viscosity; Excessive use will lead to fine mineral particles condense, leaving the foam viscosity expansion affect the flotation process of normal.

Two. Cyanide (by NaCN, KCN) Cyanide is a potent inhibitor of lead and zinc separation. Cyanide, sodium cyanide and potassium cyanide, also useful for calcium cyanide.

Cyanide is generated by the strong base weak acid salt, in the pulp a hydrolysis to generate HCN and CN-

KCN = K + + CN-

CN + H2O = HCN + + the OH-

Be seen from the above-balanced, alkaline pulp, CN-concentrations, help to curb. Such as low pH, the formation of HCN (hydrocyanic acid) make inhibitory reduce. Therefore, the use of cyanide, alkaline slurry must be maintained.

Cyanide is highly toxic pharmaceutical, over the years has been engaged in non-cyanide or less cyanide inhibitors.

3. Zinc sulfate

Zinc sulfate pure white crystals, soluble in water, an inhibitor of sphalerite, usually only inhibition in the alkaline pulp, pulp pH is higher, the inhibitory effect is more obvious. Zinc sulfate in the water the following reaction:

Of ZnSO4 = Zn2 + + SO42-

Zn2 + +2 H20 = Zn (OH) 2 +2 H +

Zn (OH) 2 as gender compounds, dissolved in acid to form salts

Zn (OH) 2 + H2SO4 = ZnSO4, +2 H2O

In alkaline medium, HZnO2-, and ZnO22- Adsorption to mineral enhances the mineral surface hydrophilic.

Zn (OH) 2 + NaOH = NaHZnO2 + H2O

Zn (OH) 2 +2 NaOH = Na2ZnO2 +2 H2O

Zinc sulfate is used alone, a total inhibition of the less effective, usually associated with cyanide, sodium sulfide, sulfite or thiosulfate, sodium carbonate and so on with.

Zinc sulfate and cyanide used in combination, can enhance the inhibitory effect of sphalerite. The commonly used ratio: cyanide: zinc sulfate 1:2-5. At this point, the CN-and Zn2 + to form colloidal Zn (CN) 2 precipitation.

4. Sulfurous acid, sulfite, and S02 gas

Sulfurous acid, sulfite, sulfur dioxide gas such preparations include sulfur dioxide (SO2), sulfurous acid (H2S03), sodium sulfite and sodium thiosulfate and so on.

Sulfur dioxide dissolve in water to generate the sulfurous acid:

S02 ten H2O = H2S03

Sulfur dioxide solubility in water decrease with increasing temperature, 18 ° C, water absorption, the sulfite concentration of 1.2%; temperature to 30 ° C, the sulfite concentration of 0.6%. Sulfurous acid and its salts have a strong reduction, it is unstable. Sulfite and a lot of metal ions to form the acid salt, bisulfite salt or normal salt (sulfite), in addition to the alkali metal sulfite salt soluble in water, normal salt of the other metals are slightly soluble in water. Sulphurous acid in water two-step dissociation, Effects of H2SO3 solution HSO3-and SO32-concentrations, depending on the pH of the solution. Sulfite flotation, mine paddle PH is often controlled in the range of 5-7. At this point, a disincentive HSO3- Sulfur dioxide and sulphurous acid (salt) is mainly used for the suppression of pyrite, sphalerite. Of dissolved lime of sulfur dioxide caused by the weak acid mine oar (pH = 5-7), or join in the use of sulfur dioxide and zinc sulfate, ferrous sulfate, ferric sulfate and other inhibitors. The galena, pyrite, sphalerite is inhibited, the inhibition of sphalerite can be activated with a small amount of copper sulfate. Can also be replaced with sodium thiosulfate, sodium metabisulfite, a sulfite), inhibition of sphalerite and pyrite.

For the copper ions strongly activated sphalerite, only poor inhibitory effect of sulfite. At this point, if you add zinc sulfate, sodium sulfide or cyanide, can enhance the inhibitory effect. Sulfite in the pulp susceptible to oxidation failure, thus, its inhibition time-sensitive. Process is stable, usually segmented added.

5 Blowing agent

Foaming agent should be organic substances of different polarity, polar, hydrophilic, non-polar base pro-gas, so that the foaming agent molecules aligned in the air and water interface, most of the foaming agent is a surfactant able to strongly reduce the surface tension of water. The table top activity of the same series of organic surfactants increase the regularity of the “third”, namely the so-called “special Fong Pui rule”. The foaming agent should be appropriate solubility. The solubility of the foaming agent has a great influence on the foaming properties and formation of bubble characteristics such as solubility is very high, the consumption of large amount of drugs, or quickly a lot of foam, but not durable when the solubility is too low, the ice was too late dissolved with the loss of foam, foaming slow duration of the principals, difficult to control.