DE2742199A1 - METHOD FOR THE BACTERIAL OXYDATION OF A FERROSAL SALT SOLUTION TO A FERRICS SALT SOLUTION AND THE RELATED DEVICE - Google Patents

Description

PATENT LAWYERS

DIPL.-ING. ALEX STENGER

D-4000 DÜSSELDORF 1 V DIPL-ING. WOLFRAM WATZKE

Malkastenstrasse 2 DIPL.-ING. HEINZ J. RING

Our reference: l8 452 Date: September 15, 1977

General Mining and Finance Corporation Limited

6 Hollard Street

Johannesburg, Transvaal Province Republic of South Africa

Process for the bacterial oxidation of a ferrous salt solution to a ferric salt solution and the associated device

The invention relates to a method for the oxidation of ferrous salt solutions and the use of such oxidized solutions to leach minerals.

It has recently been found that a ferrous sulfate solution continuous to a ferric sulfate solution in a container can be oxidized, in the spaced smooth plates or tubes with an applied bacterial layer arranged are, with the solution constantly brushing along the surfaces of the plates or pipes.

It has been found that the process is surprisingly improved or more accessible to economic use is done when the bacterial oxidation of the ferrous sulfate solution takes place in a container in which an acidified sulfuric acid are present together with a structure that is provided with honeycomb passages with a

8098 17/0636

Telephone (02 11) 36 OS 14 - Telegram address: Dabspatent ■ Postscheckkonto KBIn 2276 10 Bacterial film can be coated.

The inventive method in which a ferrous salt solution is passed through a container with an insert in the presence of oxygen at acidic pH, is characterized by that the insert is a support frame which has honeycomb-like passages, and that a on the walls of the passages Film of an oxidizing agent consisting of bacteria is applied, which oxidizes iron (II) ions to iron (III) ions, the width of the passages allowing movement of the solution.

The term "support frame with honeycomb-like passages" includes any type of structure in which a large number of passages (i.e., more than 10) are formed and a bacterial film can be deposited on the walls of the wall. Appropriately the number of passes can e.g. B. be 50 or more, preferably 100 or more. The support frame can be a prefabricated artificial structure with curved passages Act.

The frame can be a unitary structure consisting of a plurality of plates, on one or both sides of which outwardly extending relief-like formations are formed. These relief-like formations can be continuous be attached to another adjacent plate. The formation can also consist of one on one or both sides of the panels trained corrugation exist. The corrugation can be substantially wave-shaped in plan view, so that the passages are curved or twisted. The corrugation can have a substantially triangular or semicircular cross-section. In In a preferred embodiment, the frame can be attached to the mold remember a honeycomb. The ferrous salt solution can be a ferrous sulfate, e.g. B. a solution that is used, for example, in the mining industry or is used in pickling plants in steelworks. The oxidation process can be carried out using the rack

809817/0836

with its honeycomb-like passages is constantly flooded by the solution. In this case, the rate of oxidation can be high can be achieved. When the ferrous sulfate is oxidized, the resulting product can leach minerals be used, e.g. B. in the metallurgical extraction process or in the removal of sulfur from the coal.

The invention also consists in a method for the treatment of mineral materials, in which the mineral with a Ferric salt solution is leached, which is produced with the aid of the oxidation process according to the invention.

For the oxidation of ferrous ions to ferric ions, all suitable bacteria can be used, such. B. bacteria of the Genus Thiobacillus Ferrooxidana, Thiobacillus Thiooxidans, Ferrobacillus Ferrooxidans or Ferrobacillus Sulphooxidans. The reaction proceeds according to the following equation:

+ O ₃ bacteria - * - 2Fe ₃ (SO ₄ ) +

The equation shows that the conversion of ferrous sulfate to ferric sulfate requires sulfuric acid and that the The amount of ferrous sulfate determines the amount of acid required. The acid can be pure sulfuric acid or for example a mixture with other suitable acids, e.g. B. hydrochloric acid up to 10 percent by weight. To high concentrations of ferrous sulfate To oxidize, the sulfuric acid and possibly the other acids should be present in a similarly high concentration. The bacteria respond to the acidity, so that the pH is expediently between the values 0.8 to 2.5 or preferably between 1.3 and 2. A pH of around 1.5 is essential for the oxidation of ferrous sulphate particularly suitable for ferric sulfate.

It has been found to be expedient to constantly use a small amount of an acidified ferrous sulfate solution of a large amount Add iron sulfate solution, which is mainly acidified

809817/0636

Contains ferric sulfate, but which also contain other substances (e.g. Ferro and ferric chloride and hydrochloric acid) as well as bacteria and in which the frame with the honeycomb-like passages is immersed. The walls of the frame are coated with a film of bacteria. By the presence of a large The amount of mainly acidified ferric sulfate will be the Dilution of the bacteria and the pH of the solution is not unduly affected. The bacterial film is a surface film and is constantly destroyed over large areas of the surface of the honeycomb structure or passages of the frame and formed again. This allows the procedure to be carried out continuously.

The frame may be made of any suitable material having passages formed therein for the solution to flow through. The distance between two opposite sides of the walls of the passages in the rack must be wide enough to allow the solution Together with the oxygen that is carried along, the oxidant, which is made up of bacteria, can flow through it without any hindrance can. Tests have shown that the bacterial layer is generally about 1 mm thick, so that the walls of the passageways should have a distance of at least 2 mm and expediently between 3 »5 and 10 mm. It is appropriate when the growing bacteria have a maximum of space available. The surface of the frame can be made of a plastic material that is resistant to iron salts and acids. This shows a very suitable and essentially solid structure under the trademark "Flocor" from Imperial Chemical Industries Ltd. distributed material. "Flocor" is a PVC from large-pored and light structure. Under the given conditions, it is resistant to the effects of bacteria and acids. "Flocor" consists of a plurality of plane-parallel plates, which are separated by a plurality of corrugated plates and with these are connected, the corrugation of which appears undulating in plan view and has transverse ribs. The present Invention does not use basic structures such as sand and rock that can cement, and thus the passageways remain free.

809817/0636 _ ₅ _

The process can therefore be carried out without interruption. The plastic rack can be completely immersed in the container will.

The ferric salt solution may contain trace elements or other substances, that support the growth of bacteria. Such trace elements or other substances can be ammonium, nitrate, Potassium, calcium, magnesium, phosphate and chloride ions. A mixture of iron sulfates, sulfuric acid, trace elements and Bacteria can be enriched with oxygen and flow over the bacterial film on the walls of the passageways of the frame has grown. The bacterial film can also be on the Surface of the container can be provided in which the frame is arranged. Once the film has grown, it can be itself regenerate to form oxidising surfaces for an almost unlimited period of time. The container in which the bacterial oxidation taking place can be closed or jacketed to an optimal temperature range between - 10 to 45 ° C, preferably 30 to 35 ° C. The saturation of the solution with oxygen can be achieved by introducing air or oxygen into the solution by any suitable type of water aeration is performed, e.g. B. by means of a pipe, a mechanical aerator or by means of a fried slice. It has been shown that the rate of oxidation is directly proportional to the available surface of the honeycomb pattern is. The air introduced into the solution can be enriched with either pure oxygen and / or carbon dioxide will.

The container with the frame present therein can be elongated, the frame expediently being perpendicular is aligned. The ferrous salt to be oxidized can be introduced from above, while the air is introduced through the bottom will.

809817/0836

~ 3 "27Α2Ί99

The ferric sulfate solution produced with the aid of the working process is suitable as a lye liquid when leaching which uses minerals. It can thus be used to separate the sulfur from the coal or in the Extraction of metals from their ores or from waste or the like. In metallurgical extraction where bacteria are used and the caustic solution containing bacteria is circulated for reuse, the bacteria become killed by high caustic temperatures. In the present invention, the death of the bacteria is due to high caustic temperatures no further significant, after the separation of the metal and cooling, conditions prevail that the Promote renewed inoculation of the returned iron sulfate solution with bacteria.

A number of metals can be extracted from their ores with the ferric sulfate solution. E.g., uranium, copper, gold, Lead, zinc, nickel, cobalt, molybdenum, arsenic, antimony, cadmium, mercury and other basic metals.

The ore can with the help of the ferric salt solution under the action of heat and / or by stirring and / or by shaking and / or leached out by applying positive pressure if necessary. The desired metal can be extracted from the lye are separated, after which the remaining liquid can be fed back to the oxidation process. The to be treated Ores can be oxides, silicates and especially sulfides of the metal in question. Ores both lower and higher Concentration can be processed. The ores to be processed can be mine waste, copper-containing silicate gangue, Copper sulphides such as copper pebbles, copper indigo, Copper luster, copper pyrite, bornite (Cu FeS), white copper ore

(CuFe ₃ S), enargite (Cu-AsS ^), copperfahlerz (Cu ₁₂ Sb ^ S) and (

Copper screen (Cu ₁₂ As ^ S) _} nickel sulfides and nickel silicate minerals such. B. Garnierite (NigSi.0 (OH) "), nickel stone (Ni S ₂ ) iron-nickel pebbles (Fe, Ni Sg), nickel pebbles (NiS); Cobalt-

809817/0636

sulfides, arsenides or sulfur arsenides such as ζ. Β. Cobalt luster (CoAsS), tetrahydrite, a mixture of magnetic gravel with pale ore and / or with chalcopyrite, sphalerite; Selenium copper and telluride, karrollite (Co ₂ CuS.); Zinc and copper minerals such as zinc blende (ZnS), galena (PbS), a concentrate of zinc blende and galena, Pb-Cu-Fe stones, boulangerite (Pb Sb ^ S ₁₁ lead antimony ore (Pb Sb.S), Jamesonite (Pb- FeSb ^ S) and geocronite (Pb.Sb ₂ Sg); iron minerals such as liver iron ore and pyrite (FeS); molybdenum-containing minerals such as molybdenum luster (MoS); arsenic and antimony-containing minerals such as arsenic blende (AS S), arsenic gravel (FeAsS) , Antimony luster (Sb ₂ S); cadmium and mercury-containing minerals; and uranium-containing minerals such as uranite or iron blende (UO _{2 + χ} ), brannerite (Uti ^), carnotite (K ₂₂₂₄₂₂

Autunit (Ca (U0_) 2 (PO.) 10H ₀ O) and Goldschliche.

2 *

The ore can first be ground and sorted in the first stage, with the fine ore finally being placed in a tank. where it is mixed with water. The water-containing mixture can be ground further and then poured into several caustic tanks will. The contents of the caustic pot can be heated, e.g. B. by steam, and z. B. stirred by means of a stirrer or be shaken. A concentrated acid is constantly added to one or the other of the kettles in the ferric solution. After this If the lye has passed the boiler, the metals that have been washed away are filtered out and the filtrate is split into two Parts shared. One part is led to an ion exchange column (from which the metal can be gradually removed). The remaining residual solution is removed. The other part is placed in a tank in which the one is used as an oxidizing agent acting bacterial film coated honeycomb frame is included. Oxygen or air can pass through the tank from the bottom up be directed. The ferric solution obtained can be used in the caustic pot be fed back.

8098 1 7/0836

On the basis of the attached drawing, a method for carrying out the invention and an associated device are shown below explained in more detail by way of example. Show it:

Fig. 1 is a schematic work plan showing the individual steps in obtaining the Shows metals from their ores according to the invention;

2 shows a schematic sectional illustration through a tank as it is used for the oxidation of a Ferrous salt is used; and

Figure 3 is a perspective view of part of a honeycomb used in the tank Frame.

In Fig. 1, 10 denotes a mill, from which the ground ore arrives in a container or boiler 12, where it is mixed with water from line 13 and then passes through a second mill Ik. From here, the sludge, consisting of ore and water, is placed in a caustic tank 16, which is in series with other caustic boilers 16.1 and 16.2. Each caustic pot is heated by steam from a line 18 and contains an agitator 18, 18.1, 18.2.

Concentrated acid and a ferric salt solution are introduced through pipes 20 and 22, respectively. The leached material is filtered at 2k and the filtrate is passed through the pipe 26 to a point 28 where it is divided approximately into two equal parts. The residue from the filter is discharged through line 30 and is available.

One part of the lye solution is passed through a pipe to an ion exchanger Jk , from where the outlet is removed through pipe 36. The other part of the leach solution through a pipe 38 into a tank kO

8098 1 7/0636 - 9 -

given, in which a submerged support frame 42 is contained, which is provided with honeycomb-like passages. This tank and the support frame are shown more clearly in FIGS. The walls -44 are honeycombed in appearance and triangular in cross-section.

The liquor liquid flowing through the conduit 38 is an acid solution mixed with ferrous salt, which may also contain some ferric salt. The solution flows through the channels or passages 43 in the support frame, its walls are coated on their surfaces 45 with a bacterial oxidizing agent. The aerator 46 is by means of a Pump 48 air naph pushed up. The solution is oxidized by the bacteria in the presence of the air, with the resulting Ferric salt solution is fed back through the pipeline 22 to the working process. The metal is dated from time to time Exchanger 34 elutes by pulling the eluate from line 50 through flows through the exchanger and the solution containing the metal is collected through the pipe 52.

The invention will be elucidated with reference to the following examples illustrated without any restrictions.

Example 1;

A cylindrical tank 3 ■ high and diameter of 1.2 m was filled with ferrous sulfate solution. The volume of the solution was 3,400 1. A block of honeycomb-like Elements of the frame shown in Fig. 3 made of the material "Flocor" and with the dimensions 1,000 × 1,800 × 600 mm was integrated into the

Immersed tank liquid. The specific surface area

2 Ί
was 93 m / m. The ventilation took place at the bottom of the tank by a conventional aerator, which supplies 50 m / hour nominal air. After a few weeks in which the activity of the bacteria (Ferrobacillus ferrooxidans were used) increased and reached a maximum, the following data were measured:

809817/0636 " ¹⁰ "

Rate of oxidation per unit area

temperature pH 32 ° C Feed-in speed Rate of oxidation 72 l / hour Feed ferro Surface area 9.8 g / l Ferric 1.3 g / l sulfuric acid 9.0 g / l Product Ferro 0.25 g / l Ferric 10.5 g / l sulfuric acid 0.88 g / l 1.5 688 g / hour 100 m ²

6.88 g / m / hour

The distance between the walls of the passages in the honeycomb was approximately 4 mm.

The solution prepared from ferric iron and bacteria was added to an ore according to the working diagram of FIG Contains mineral and pyrite. The ore was made with sulfuric acid acidified to remove any remaining alkalinity.

Example 2; (Comparative example)

Various other ways of oxidizing ferrous sulfate have been compared, as explained below. The used Devices were:

1. A plate and spray unit

In this device, the ferrous sulfate solution was over sprayed several plates coated with bacteria. The ferric sulfate was collected on the bottom.

2. A bio disc unit

In this device, a shaft with several bacteria-coated disks in an iron sulfate solution was used rotated, with fresh ferrous sulfate solution was added at one end.

809817/0636

- 11 -

AH

Packing filter unit

A ferrous sulfate solution was used in this device • In a turn directed downwards, which is equipped with rings and coated with bacteria.

A submerged honeycomb-like unit

In this device (see drawing) the ferrous sulfate entered into an iron sulfate solution, in which an insert coated with bacteria according to the construction shown in FIG was immersed. The air was supplied from below. This process is called the "Bacfox" process.

Thiobacillus ferrooxidans were used in all cases. The ferric sulfate was used to leach ground ore. In all cases the following values were used:

Treated solution
Ferrous iron concentration of total ferrous iron produced

66560 t / month

5.0 g / l

460 kg / hour

The following table summarizes the rate of oxidation and the capital and labor costs.

unit

Fe rate of oxidation

2 Ί

g / m / hour g / nr / hour

Capital labor costs

R R / t Cent / kg hand. made Solution Ferric

Plate and
Sprayer 5.5 344 ND 000 0 ND 2 ND Bio disk 3.78 204 558 000 0 , 145 2 , 91 filter
pack 1.125 212 548 800 0 , 145 0 , 91 Bacfox
procedure 7.46 693 113 , 031 , 63

- 12 -

809817/0636

The economic advantages of the invention are evident.

Example 3:

In the part of the working diagram shown in FIG. 1 which is separated off for leaching, 500 g of ground ore, which contains an equivalent of 0.36 kg of U 0.1 / t, are slurried with water. The sludge was then ground and then placed in the caustic pot 16, where 350 g of ferric sulfate solution from the tank 40 (prepared according to Example 1) was added. This solution contains 8 g of ferric iron. An equivalent of 15 kg of concentrated sulfuric acid was added per ton of ore, after which the sludge was leached at 55 ° C. for 2 hours. Then an equivalent of 1.0 kg / t of MnO _{0 was} added in order to oxidize all ferrous ions contained. The leaching continued for an additional 16 hours.

The slurry was filtered, washed, dried and tested. The uranium content of the leached residue indicated that 90 % of the uranium had been leached from the ore.

A control test using the same ore but not ferric sulfate made according to the invention required 25 kg / t of sulfuric acid and 3 to k kg / t of MnO for oxidation.

example k:

(a) The working method shown in Fig. 1 can be carried out with Covellite carried out as ore and ferric sulfate acid at about 35 ° C or with a ferric chloride acid and a ferric sulfate mixture at about 98 ° C for leaching.

(b) When repeating the copper luster working procedure Temperatures in the range between approximately 23-95 C can be used.

8098 1 7/0636

- 13 -

(c) When repeating the working procedure for copper pebbles Temperatures in the range between approximately 27-100 C can be used.

(d) If the procedure is repeated for bornite, temperatures used in the range between approximately 23-98 ° C will.

(e) When repeating the white copper ore working procedure and when using ferric sulfate, temperatures are in a range of approximately 45 - 90 ° C is expedient.

(f) If the procedure is repeated for enargite and using ferric sulfate, temperatures will range between approximately 60 - 95 ° C is advisable.

(g) When repeating the procedure for copper ore and using ferric sulfate, temperatures of approximately 35 C appropriate.

(h) By repeating the procedure for pentlandite and using ferric sulfate, temperatures in the range between 25 and 60 ° C.

(i) When repeating the procedure for pyrrhotite and use of ferric sulfate, temperatures can range from about 32-50 ° C.

(j) If the procedure is repeated for pyrite and using ferric sulfate, the temperature may be approximately 33 ° C.

example 5 '

The procedure of Example 1 was repeated, but using Thiobacillus Ferrooxidans to make a ferrous sulfate and to oxidize a ferro-hybrid mixture containing 6.8 g / l FerrocHbrid and 13.6 g / l ferrous sulfate. There was one

809817/0836

Mixture of perric chloride and perriesulphate. That is a stronger oxidizing agent than ferric sulfate alone and can therefore be used even better for leaching the minerals will.

809817 / 0B36

Claims (9)

PATENTANWÄLTE DIPL.-ING. ALEX STENGER D-4000 DÜSSELDORF 1 DIPL.-ING. WOLFRAM WATZKE Malkastenstvaße 2 DIPL.-ING. HEINZ J. RING Our reference: 18 452 Date: I5. September 1977 General Mining and Finance Corporation Limited Hollard Street Johannesburg, Transvaal Province Republic of South Africa PATENT CLAIMS 1. A method for the bacterial oxidation of a ferrous salt solution to a ferric salt solution, in which a ferrous salt solution in the presence of oxygen at acidic pH is passed through a kettle with an insert, characterized in that the insert is a support frame (42) which has honeycomb-like passages, and that a film of an oxidizing agent consisting of bacteria is applied to the walls (kk) of the passages, since iron (II) ions oxidize to ferric (III) ions, the width of the passages allowing movement of the solution. 2. The method according to claim 1, characterized in that the support frame is composed of a plurality of plates, which are provided with surveys, z. B. a corrugation that extends outwardly from both sides of the plates. 3. The method according to claim 1 or 2, characterized in that the ferrous salt is a ferrous sulfate. 8098 17/0636 Telephone (0211) 36 OS H · Telegram address: Dabspatent ■ Postscheckkonto Cologne 227 * 10 4. The method according to any one of claims 1 to 3 »characterized in that that the pH is in the range between 0.8 to 2.5, preferably 1.3 to 2. 5. The method according to any one of claims 1 to k, characterized in that the bacteria belong to the genus Thiobacillus Ferrooxidans or Ferrobacillus Perrooxidans. 6. The method according to any one of claims 1 to 5, characterized in that that the produced ferric salt solution is later used for leaching minerals. 7. The method according to claim 6, characterized in that the mineral material is an ore in which more or less Uranium, copper, gold, lead, zinc, nickel, cobalt, molybdenum, arsenic, antimony, cadmium or mercury, coal with sulfur, or mineral mine waste 8. The method according to claim 6 or 7, characterized in that the ferric salt solution used as the lye liquid is then treated for the purpose of removing the leached material and subsequently fed back into the process to remove the leached material To oxidize ferrous salts to ferric salts. 9. The method according to claim 8, characterized in that the Leached material is removed by adding the leach liquid is passed through an ion exchange column. 10. Apparatus for the production of a ferric salt according to A method according to claim 1, comprising a vessel in which an insert is used as a carrier for a bacterial oxidant is provided and which has an inlet for air or oxygen and at one end with an inlet for one acidified ferrous salt solution and at the other end with one Outlet for a ferric salt solution is provided, thereby marked 809817/0 ^ 36 " ³ " indicates that the insert is a support frame (42) which has honeycomb-like passages for the liquid whose Walls are coated with a bacterial film that is capable of oxidizing a ferrous salt solution and that is dimensioned so that that an acidified ferrous sulfate solution can flow through. 11. The device according to claim 10, characterized in that the frame is made of plastic and the passages in Plan view are wavy. 9 817/0636