EA006041B1 - Method of assaying and apparatus therefor - Google Patents

Abstract

The invention provides a method of assaying a mineral sample for determining the concentration of selected metals in a sample comprising the steps of providing a comminuted mineral sample; mixing such sample with a flux; preheating a reaction vessel to a temperature which approximates the melting point of the flux; introducing the mixture of the mineral sample and flux into the crucible, whereby the mixture is transformed to a molten state to capture the metal to be assayed in a collector material; and separating slag from the collector material. The collector material is brought into contact with oxygen or oxygen forming material for oxidation of the collector material or a part thereof prior to or after melting the mixture to reduce the volume of said material prior to or after separating said collector material from slag.

Description

This invention relates to a quantitative analysis, in particular, but not exclusively, to the determination of the gold and / or platinum group metals in an ore sample.

In practice, it is common practice to analyze ore in the exploration and development of gold or platinum to determine the amount of the presence of gold or platinum group metals (platinum, palladium, rhodium, osmium, iridium and ruthenium).

The usual process of analysis is known as the “dry sample”. The process involves weighing a sample of crushed ore and mixing it with a flux that carries lead oxide or with a nickel flux. The mixture is then placed in a crucible and heated to elevated temperature, usually about 1100-1250 ° C for about 60-90 minutes.

During this process, the mixture is melted, lead oxide is reduced to metallic lead, or nickel sulfide is formed, and lead or nickel sulfide collects (picks up) platinum group metals and / or gold due to their chemical affinity.

The molten slag and trapping material is poured into the mold and left to cool. Lead and nickel sulfide precipitate to the bottom of the mold. After cooling the mold, lead and lead nickel are separated from slag using mechanical techniques. The procedure is labor intensive. After separating the trapping material from the slag, it is placed in the assay dish, preheated to 1000–1300 ° C to ensure the absorption of lead by cupellation. The result is a tiny granule remaining at the bottom of the cup. Then you can determine the content of platinum group metals and gold in the granule using various analysis technologies.

In addition to the time-consuming process described above, it was found that during the loading and removal of reaction vessels or crucibles from the furnace to perform a dry sample, there is a significant loss of energy, which leads to an additional slowdown of the analysis process.

As for the fluxes used in the dry sample process, the usual flux components include borax (sodium borate hydrate), sodium carbonate, lead glt (lead monoxide), silicon dioxide, coal, fluorspar, red lead (Pb ₃ O ₄ ), potassium nitrate and iron.

The purpose of this invention is to create a new method of accumulation of metals in a sample of minerals in the process of quantitative analysis, as well as devices for implementing this method.

Summary of Invention

A method for quantitative analysis of a mineral sample to determine the concentration of selected materials in a sample; it contains the steps of preparing a sample of ground mineral;

mixing this sample with the flux that forms the trapping material during its melting;

placing the mixture in the reaction vessel and preheating the reaction vessel to a temperature that is approximately equal to the melting point of the flux, whereby the mixture enters the molten state with the formation of slag and ensuring the capture of the metal to be analyzed, catching material; and the separation of slag from the collecting material.

According to the invention, the trapping material is brought into contact with oxygen or an oxygen-forming material to oxidize the trapping material or part of it before or after melting the mixture to reduce the volume of this material before or after separating the trapping material from the slag.

Thus, in this method, the reoxidized trapping material is again captured by the flux slag. This method can be applied to conventional analysis processes in which the reaction vessel is not preheated.

It is possible for the trapping material to be oxidized by supplying oxygen or an oxygen generating material to the reaction vessel. Oxygen is preferably introduced into the trapping material with a spear or the like.

In another embodiment, a reaction vessel is used which is provided with an outlet at a lower level, and oxygen is introduced into the reaction vessel through an outlet at the lower level to re-oxidize the trapping material. After that, the trapping material can be discharged through the outlet located at the lower level for further analysis.

In addition, according to this aspect of the invention, the method may include the step of introducing into the reaction vessel a separate catcher for a material to be analyzed, such as silver or gold.

Alternatively, the method of the invention may include the step of separating the capture material from the slag formed during the melting process and then bringing the capture material into contact with oxygen or with the oxygen-forming material to oxidize the capture material or part thereof. In this embodiment, the oxygen stream is preferably blown onto or into the trapping material for oxidation. Thus, in cases where the trapping material contains lead, this lead is oxidized to lead oxide, which is removed by evaporation. Catching material, such as silver, that is not capable of light

- 1 006041 oxidation, remains for analysis purposes.

In yet another embodiment, oxygen may be introduced into the separation vessel from the source through a manifold, which hermetically encloses the separation vessel below its outlet.

In this embodiment, the method preferably comprises the step of detaching the manifold from the separation vessel to ensure that the trapping material is drained into this manifold. Thus, the pressure in the reservoir serves to close the outlet channel before disconnecting the manifold from the separation vessel.

After unloading the trapping material into the collector, the material is melted and form a granule and then this granule is placed on a suitable transporting means for further processing.

The scope of the present invention also includes a device suitable for use in the above method, comprising a reaction or separation vessel having an outlet channel located at a lower level and a collector under the outlet channel, as well as a spear passing into the vessel to introduce oxygen into the vessel.

The collector is made with the possibility of hermetic separation of the separation vessel and has an entrance for passing oxygen / gas through the internal space of the collector.

In a preferred embodiment, the front end of the lance is made in the form of a plug for the outlet of the vessel and is installed with the possibility of longitudinal movement in the direction to and from the opening for closing or opening this opening.

The separation vessel preferably comprises a downwardly directed tubular structure projecting from the outlet channel to which the manifold is hermetically pressed.

Separating the trapping material from the slag is carried out by providing a trapping material that has a higher density and / or lower viscosity than the slag, and using a separating vessel that is equipped with an exhaust channel, and releasing the trapping material through this exhaust channel, while the dimensions of the exhaust channel such that the trapping material passes through it, while the slag lingers on the channel. The discharge channel is preferably located at the bottom of the vessel.

The separating vessel specified above, in one of the embodiments, has a predominantly conical shape in the section, with the outlet channel located at the bottom of the top of the cone. When the trapping material is lead, the discharge channel may be, for example, of circular cross section with a diameter of from 0.5 to 2.0 mm, preferably about 1.0 mm.

In addition, the stage of separating the trapping material from the slag can be carried out using a separating vessel, which has an internal concavity ending in the lower part to receive the trapping material, and which has an outlet channel located at a distance from this lower part, while the reaction and separation vessel rotated in the transverse direction, so that the trapping material in the lower part flows to the area of the exhaust channel, and it is released through the exhaust channel. As indicated above, the dimensions of the outlet channel are such that the trapping material can pass through it, while the slag is held up.

Thus, the vessel has a lower part for receiving the trapping material and an exhaust channel located at a distance from this lower part, while the exhaust channel is designed so that the trapping material is able to pass through it, while the slag is delayed, and the concavity in the outlet zone the channel provides reception of the trapping material when the reaction and separation vessel is rotated at an angle to allow the trapping material to flow into the outlet channel zone.

A flux suitable for use in the dry sample method according to the invention contains a trapping material capable of combining with the material in the mineral sample to be collected and potassium hydroxide. For most applications, the flux contains between 5 and 60 wt.%, Preferably 7.5 wt.% Potassium hydroxide.

In addition, the flux contains one or more additional compounds selected from the group of alkaline earth metal compounds. These alkaline earth metal compounds are preferably hydroxides. While the flux may contain between 5 and 60 wt.%, Preferably 7.5 wt.% Calcium hydroxide.

In addition, the flux may contain one or more additional compounds from the group of alkali metals, preferably hydroxides. For example, the flux may contain between 10 and 19 wt.% Sodium hydroxide.

Brief Description of the Drawings

Below is a detailed description of some embodiments, solely as examples, with reference to the accompanying drawings, in which FIG. 1 is a schematic diagram of the steps of a quantitative analysis method according to the invention;

FIG. 2-3 - sections of the reaction and separation vessel, which is used in the method according to the invention, illustrating the various stages of this method;

FIG. 4 and 5 are sections of the second variant of the reaction and separation vessel, which is used in the method of quantitative analysis, according to the invention, illustrating the various stages of this

- 2 006041 method;

FIG. 6 and 7 are sections of the third variant of the reaction and separation vessel, which is used in the quantitative analysis method according to the invention, illustrating the various stages of this method;

FIG. 8 and 9 are sections of the fourth variant of the reaction and separation vessel, which is used in the method of quantitative analysis, according to the invention, illustrating the various stages of this method.

Description of drawings and examples of the invention

The method of quantitative analysis according to the invention comprises the steps shown in FIG. 1. These stages contain a stage of preparation of a mineral sample, designated 10, usually in the form of a dry powder, and a stage 11 of mixing a given mass of such a sample with a specified amount of a suitable known flux that contains lead oxide, nickel or other materials capable of forming a trapping material for metal mineral to be analyzed. The method according to the invention is intended, in particular, but not exclusively, for the quantitative analysis of gold or platinum group metals.

Then, the mixture prepared in this way is placed in stage 13 in a reaction vessel. A feature of this invention is the preferred preheating in stage 12 of the reaction vessel to a temperature in the range of the melting point of the mixture in a suitable furnace or the like. This furnace can be, for example, a gas, electric, or induction furnace. After placing the mixture in the reaction vessel, additional thermal energy is supplied to this vessel in stage 14 to maintain its temperature at the melting point of the mixture.

After the mixture is melted in step 15, a trapping material is obtained, such as lead or nickel sulfide, which collects gold and platinum group metals due to chemical affinity. Then, the trapping material can be separated from the slag in the manner indicated below for analysis.

According to the invention, it is provided to reduce the trapping material in volume at stage 16 and, if necessary, to concentrate with additional trapping material at stage 17 to facilitate the analysis process. This decrease in volume is shown in FIG. 2 and comprises the step of introducing oxygen 23 into the trapping material 24, for example, with a spear 21, which is lowered into the reaction vessel, indicated in FIG. 2 position 19. Thus, oxygen 23 reacts with a lead-collecting material 24 or another oxidizing material-collecting material and oxidizes lead to lead oxide, which is again captured by slag 25. Using this method, you can leave a small amount of material 24, for example , lead for analysis at stage 18, or concentrate in additional trapping material, such as silver or gold, which is better amenable to analysis, for example, using spark spectrometry. Thus, the invention provides for the possibility of adding a separate additional capture material to the mixture before or after melting.

As an alternative to the use of the spear 21, the molten collection material 24 can first be separated from the molten slag 25 and placed molten in a test tube, and brought into contact with a rich source of oxygen at this stage, due to which the collecting material 24 is oxidized or partially oxidized. As mentioned above, the trapping material 24 may contain lead, which is oxidized under such conditions, together with silver as an additional trapping material, which is not easily oxidized. Thus, during the oxidation process, silver remains to form a granule that contains the metal to be analyzed. Such a granule can be subjected to analysis, in particular, chromatographic analysis of the emitted gases. Thus, this source of oxygen can again be, for example, a spear 21 used to blow oxygen onto or into the capture material 24, or alternatively, an oxygen-forming salt can be introduced into the capture material 24.

Alternatively, as shown in FIG. 9, oxygen can be introduced through the outlet 20 of the reaction vessel 19 at the bottom level through the collector vessel 131 and the tubular extension 121 of the reaction vessel 19.

The method according to the invention also includes the step of separating the molten collection / additional collection material 24 together with the gold or platinum group metals contained therein from the molten slag 25.

Example 1 of the separation vessel.

In one embodiment, the method is carried out using the separation vessel 19 shown in FIG. 2 and 3.

The vessel 19 has a generally conical profile with the top of the cone 19a downward. Coaxially to the vessel 19 at the bottom of the cone apex 19a, there is an outlet channel 20 configured to discharge the trapping material 24 from the vessel 19 into a suitable vessel or form 26 (see FIG. 3). The invention provides that the trapping material 24 has a higher density and / or lower viscosity than the molten slag 25, and the dimensions of the exhaust channel 20 are such that only the trapping material 24 is able to flow through the channel 20. Thus, in the case of

- 3 006041 lead, lead can easily flow through the exhaust channel 20, while the molten slag 25 is retained at the exhaust channel 20 and is unable to pass through it due to its low density and viscosity, as shown in FIG. 3. It has been found that the outlet channel 20 is suitable for a generally circular cross-section with a diameter between 0.5 and 2.0 mm, preferably about 1.0 mm.

It is clear that the size of the orifice can be adapted to be adjusted in accordance with the requirements, for example, by providing a valve (not shown) or a plug for this outlet channel 20. One such system is shown in FIG. 2, in which the oxygen lance 21 ends with a stopper 22 that is movably mounted between a position in which it lies against the lower end of the top 19a of the vessel 19 for sealing the discharge channel 20, and a position in which the stopper 22 is removed from the top 19a of the vessel 19 for opening the outlet channel 20. With this system, the separation vessel 19 can also be used as a reaction vessel by closing the outlet channel 20 until it is necessary to separate the trap material 24 and the slag 25. Thus Braz, during step 15, melting the mixture and the step 16 (see. Fig. 1) oxidation of the material of the collecting tube 22 is in the closed position. It is then opened to effect the separation of the trap material 24 and the slag 25 in the manner indicated above.

Example 2 separation vessel.

In this example, shown in FIG. 4-7, the reaction and separation vessel 29 comprises a housing that forms an internal concavity 32, which includes the lowermost portion 32a for receiving the capture material 24 during the analysis procedure. Thus, during the process of melting the mixture from the flux material and the mineral sample, catching material 24 is formed in the form of lead or nickel sulfide, or silver or the like, and serves to capture the gold and platinum group metals present in the mineral sample. The trapping material 24, which has a greater density, settles in the lowest zone of the reaction and separation vessel, while the slag 25, which includes waste rock, covers the trapping material 24. As mentioned above, oxygen can be introduced into the trapping material 24 to oxidize all or parts of the material, which is then again absorbed by the slag 25.

The reaction and separation vessel 29 is characterized in that an outlet channel 20 is provided, which is located outside the lowest zone 32a of the concavity 32, which receives the trapping material 24. In the systems shown, the outlet channel 20 is located in the side wall of the vessel 29, but the invention is not limited to this position and there are also other working positions.

A feature of the invention is that the trap material 24, or its residue after oxidation, is separated from the slag 25 by turning the reaction and separation vessel 29 in the transverse direction, so that the trap material 24 flows into the area of the outlet channel 20 and is received by the concave zone 30 near the outlet channel . From zone 30 near the outlet channel, the trap material 24, due to its higher density and / or lower viscosity, can be discharged through the outlet channel 20, while the slag 25 is delayed and cannot flow through the channel 20. As mentioned above, the diameter of the circular outlet channel 20 may be between 0.5 and 2.0 mm, preferably 1.0 mm.

Near the outlet channel 20 there is preferably a concave zone 30 into which the catching material 24 flows before or during the discharge through the channel 20. If necessary, a groove or channel may be provided on the inner surface of the vessel 29 to guide the catching material from the lowest part at the top 32a of the vessel 29 to the outlet concave zone 30.

In the embodiment shown in FIG. 4 and 5, the vessel 29 is rotated approximately 90 ° to bring the outlet channel 20 to the lowest position when the vessel 29 is turned in order to drain the trap material 24 from it. In the shown embodiment, the outlet channel 20 is located in the side wall of the vessel 29, however, it is clear that this position may change if necessary and may be, for example, in the lid of the vessel. It should be noted that the position of the outlet channel 20 determines the angle of rotation of the vessel 29 to ensure the flow of catching material 24 to this outlet channel 20 for the purpose of discharge.

In the embodiment shown in FIG. 4 and 5, the concave region 30 of the discharge channel is formed by an outward-directed bulge 29a of the side wall of the vessel 29.

In the alternative embodiment shown in FIG. 6 and 7, the concave area 30 of the outlet channel is formed by the inward section 29b of the inner wall of the vessel 29. In this embodiment, the vessel must be rotated by an angle that is greater than 90 ° to position the vessel 29 so that the concave area 30 near the outlet channel is in the low point. In this position, the slag 25, or at least part of it, flows out of the vessel 29, as shown in FIG. 7, and it can be assembled separately. Thus, in this embodiment, all the slag 25 can be discharged in this position, while the trapping material 24 is discharged through the channel 20.

In both exemplary embodiments, as shown in FIG. 4 and 5 and FIG. 6 and 7, the discharge channel 20 may be provided with a valve or closing means for selectively draining the collection material 24 from the vessel.

- 4 006041

Example 3 separation vessel.

As shown in FIG. 8 and 9, the separation means for use in the quantitative analysis method according to the present invention comprises a separation vessel 19, which generally has a conical shape and which ends at a lower level outlet channel 20. Below the exhaust channel 20 from the separation vessel 19, the ceramic passes downwards pipe 121 of small length.

In addition, the device includes a collector or collector form 131, which is located coaxially under the ceramic pipe 121 and which is mounted for movement by means of a lifting mechanism 141, such as a hydraulic follower, from a position remote from the ceramic pipe, as shown in FIG. 8, to a position in which it slightly covers the ceramic tube, as shown in FIG. 9. In addition, the collector form 131 has in its side wall an inlet 15 for oxygen 161. Thus, in this embodiment, oxygen 161 can be introduced from an unrepresented oxygen source into the separation vessel 19 through the internal space of the collector form 131 and through the outlet channel 20 separation vessel 19.

In the method of analysis using the above device, a mixture of a crushed mineral sample and a flux used for the analysis is introduced into a separation vessel. The flux includes, for example, lead oxide, which forms slag and lead during the reaction, the latter being combined with gold and / or platinum group metals due to chemical affinity. At this stage, heat is supplied to the separation vessel and / or the material inside it. As mentioned above, the separation vessel can also be preheated. At this stage, the collector form 131 is in engagement with the ceramic pipe 121, oxygen 161 is supplied and introduced into the separation vessel 19 through the internal space of the form 131 and the exhaust channel 20, while molten slag and lead are added to the separation vessel 19. After a sufficient time the oxygen supply is stopped. At this stage, the trapping material, such as lead, is again oxidized to minium for absorption by the molten slag.

However, the pressure in the collector form 131 at this stage limits the flow of material through the outlet channel 20 of the separation vessel 19. The next stage of the process involves separating the collector form 131 from the separation vessel 19 using a hydraulic pusher 141, which leads to the discharge of the collected material 24 through the outlet channel 20 collector form 131. The diameter of the outlet channel 20 is such that the relatively dense and low-viscosity material collected 24 passes through the channel 20, while the slag 25 is trapped inside the vessel 19 The collector form 131, which is relatively isolated from the heat of the separation vessel 19 by the ceramic tube 121, is relatively cold, and the collected material 24 quickly solidifies in the collector form 131 to form a granule of material. After that, the collector form 131 can be tilted to unload the granules onto a suitable conveyor means (not shown) for further processing. At this stage, it is also possible to tip the separation vessel 19 to discharge the slag 25 remaining in the vessel 19, which can be immediately reused.

According to another aspect, the invention includes the creation of a new flux, which, as stated, provides a particularly short reaction time.

In one exemplary embodiment, the flux, according to the invention, suitable for the analysis of gold ore and platinum-group metal ores, may have the following composition, wt.%

Potassium hydroxide 7.5 Calcium hydroxide 7.5 Sodium hydroxide ten Borax 31 Litharge thirty Sodium carbonate 7.0 Silica 6.5 Coal 0.5 In practice, this composition is used in an amount of about 200 g for the analysis of gold ore or ore of

talent platinum group. For mine tailings, flux can be used in amounts up to 500 g.

It was found that the above composition leads to a strong increase in the melting rate of the flux during the analysis.

In addition, it was found that the effect of potassium hydroxide is further enhanced by the addition of sodium hydroxide. It was found that a synergistic effect is created when using these two alkali metal hydroxides.

The exact composition of the flux varies according to the type of ore to be analyzed. For example, the content of potassium hydroxide can vary between 5 and 60%, calcium hydroxide between 5 and 60% and sodium hydroxide between 10 and 19%. In addition, the flux composition may include fluorspar, minium, potassium nitrate and iron.

Those skilled in the art will appreciate the advantages of various aspects of the invention. The stages of the method according to the invention are easily amenable to mechanization and computerization. Understand

- 5 006041 but that this increases the accuracy of the analysis and greatly reduces the time required for analysis.

Naturally, various modifications of the details of the invention are possible without departing from the principles set forth in the following claims.

Claims (12)

1. A method of quantitative analysis of a mineral sample to determine the concentration of selected metals in a sample, comprising the steps of preparing a sample of ground mineral, mixing a mineral sample with a flux that forms a trapping material during its melting, placing the mixture in a reaction vessel, and ensuring the mixture is melted, thereby the mixture goes into a molten state with the formation of slag and providing capture of the metal to be analyzed by the trapping material, separating the slag from the trapping material, I distinguish wherein the capture material is brought into contact with oxygen or oxygen-forming material to oxidize the capture material or part thereof before or after melting the mixture to reduce the volume of this material before or after separation of the capture material from the slag. 2. The method according to claim 1, characterized in that the trapping material is oxidized by introducing oxygen or oxygen-forming material into the reaction vessel after melting the mixture before separating the trapping material from the slag. 3. The method according to claim 2, characterized in that oxygen is introduced into the capture material using a spear or similar device. 4. The method according to claim 2, characterized in that oxygen is introduced into the capture material through an outlet located at a lower level to drain this material from the reaction vessel. 5. The method according to claim 1, characterized in that oxygen is introduced into the separation vessel through an outlet located at a lower level to discharge the collection material from the separation vessel from the oxygen source through a collector mold that tightly covers the separation vessel below the outlet. 6. The method according to claim 5, characterized in that it includes the step of separating the collector form from the separation vessel after oxidation of the capture material to ensure that the capture material is drained into this collector form through an outlet. 7. The method according to any one of claims 1 to 6, characterized in that it includes the step of introducing an additional oxidation-resistant capture material into the reaction vessel after or before melting the mixture and before the oxidation of the capture material. 8. The method according to claim 7, characterized in that the additional trapping material is silver or gold. 9. The method according to claim 1, characterized in that it includes the step of separating the trapping material from the slag formed during the melting of the mixture, and bringing the trapping material into contact with oxygen or with the oxygen-forming material to oxidize this material or part thereof to reduce the amount of trapping material. 10. The method according to claim 1, characterized in that the flow of gaseous oxygen is blown onto or into the trapping material for oxidation. 11. A device suitable for use in the method according to any one of claims 1 to 3 or 7-10, characterized in that it contains a reaction or separation vessel and a spear passing into the vessel for introducing oxygen into the vessel. 12. The device according to claim 11, characterized in that the front end of the spear is made in the form of a plug for the outlet of the vessel and the spear is installed with the possibility of longitudinal movement towards and from the hole for closing and opening this hole.