FI65815C - REFERENCE TO A FOLLOWING METAL SHEET METAL - Google Patents

Description

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Patent ceddelat '(51) Kv.lk?/IntCI.3 C 22 B 47/00, 19/22 S (JQ | M || _ | S || ^ | a ^ | ^ Q (21) Puanttlhakimus - Pat * nuna6fcnln | 761659. (22) HtkemUpJUvi —An * öknlnf »d« | 09 · 06.76 '' (23) AlkuptWi — Glklfh * t »l» | 09.06.76 (41) Tullut lulktetkti - Blfvtt off «MU |] Q Q1 77 yttl. |. R.kl ^ rih.mtu.

och r * gitt * r * tyr «lMn v 1 AnXMon utltfd och utljTrKtM puWJe # r» d 30.03.84 (32) (33) (31) Fjrydetijr ttuoHnu »lt | M priortuc 09.07.75 03.05.76 USA (US) 594278, 682442 (71) Newmont Exploration Limited, 44 Briar Ridge Road, Danbury, Connecticut, USA (72) Leonard Harris, Cos Cob, Connecticut, Alfred Kenneth Hanson, Jr.,

Danbury, Connecticut, USA (74) Berggren Oy Ab (54) Method for removing manganese from metal-containing solutions -Förfarande för avlägsnande av mangan ur metallhaltiga lösningar

Excessive manganese in metal-containing solutions such as metal extracts, which are to be treated by electrolytic procedures to recover metals, has caused problems such as reduced current efficiencies during electrolytic recovery of the desired metal at cathodes and manganese deposition on the anodes and poor physical properties of recovered metals.

This problem of manganese and its accumulation in solutions and precipitation of the desired metal has been overcome to some extent in electrolysis plants by using a more reactive anode or dropping a portion of the solution to neutralize and separate the desired metal by chemical precipitation before further processing. Thus, for example, in the electrolytic recovery of zinc, chemical lead anodes have been used instead of normal lead / silver alloy anodes. Other attempts to overcome the problems are a method of cleaning the manganese precipitate from the anodes and cells more frequently, which is expensive and time consuming especially when large amounts of manganese are dissolved in the liquid. Besides, in some procedures involving the removal of manganese, manganese occurs. / 2 65815 During the removal step, undesired removal or loss of significant amounts of the metal to be recovered.

With particular regard to zinc recovery by electrolysis, this problem of manganese contamination of the electrodes is exacerbated when the "Jarosite process" is used in zinc recovery. The "Jarosite process" is a well-known iron removal process used after highly acidic extraction, which can increase zinc recovery from roasted sulfide concentrates by an electrolytic zinc process. To the extent that it has been found out, the roasted zinc concentrate is subjected to a strong sulfuric acid extract, followed by treatment using preferably ammonium ion to precipitate iron to obtain a zinc sulphate-free iron solution with very low zinc losses. With such a highly acidic extraction, there is even more dissolution of manganese in the roasted zinc sulfide concentrate, causing increased problems of electrode fouling and desired zinc precipitation during electrolytic zinc recovery.

The present invention provides a method for removing soluble manganese ions as insoluble gamma-manganese dioxide from zinc sulphate-containing solutions without excessive loss of zinc, which is to be recovered, in particular for removing manganese from extraction solutions from which said metal is to be recovered by electrolytic processes. The present invention further provides a process for preparing an easily filterable ore slurry containing gamma-manganese dioxide.

Briefly, the present invention comprises the steps of treating said zinc sulphate-containing solution with an oxidizing agent capable of oxidizing soluble manganese ion to insoluble gamma-manganese dioxide at a temperature and for a time sufficient to precipitate at least 90% of the manganese ion in said solution. as manganese dioxide, said oxidizing agent being about 130-150% of the theoretical amount required for substantially complete removal of manganese from said solution, and separating said precipitate from said solution. In a preferred embodiment, the present invention comprises an improvement in the "Jarosite process" for zinc recovery, wherein prior to electrolytic zinc recovery, the extraction solution is treated with a persulfate oxidant such as ammonium persulfate to oxidize the soluble manganese ion to deoxide precipitation, which results in the removal of iron from the extraction liquids.

The only illustration in the drawing is a flow chart of an electrolytic zinc process that incorporates the "Jarosite process" and includes an improvement of the present invention regarding the removal of manganese ion prior to electrolytic recovery of zinc.

The following description and examples discuss the applicability of the present invention to the selective removal of soluble manganese ion as insoluble gamma-manganese dioxide from zinc solutions, especially zinc sulfate solutions, which is a preferred embodiment of the invention. It is to be understood, however, that the description provided herein with respect to conditions that are optimal and / or preferred for the selective removal of manganese ions from zinc sulfate solutions is applicable to the removal of such ions from solutions containing other metals such as copper, nickel, cobalt, cadmium and mixtures thereof.

Although other manganese-containing solutions can be successfully treated in accordance with the process of this invention, it is particularly advantageous in the treatment of metal sulfate solutions in general and zinc sulfate extraction solutions in particular. In addition, although it is desirable to treat extraction fluids that are to be electrolysed to recover zinc, the invention can be used to treat any fluids from which it is desirable to selectively remove manganese.

With respect to the oxidizing agent used in the present invention, it is necessary to use an agent capable of oxidizing the soluble manganese + 2 ion Mn to insoluble manganese dioxide. There are numerous oxidants that can achieve this result and the choice depends mainly on economic factors and the fact that in some cases it is not desired to introduce harmful elements into the solution. In the case of, for example, the electrolytic zinc plant cycle, it would not be appropriate to use oxidants containing lead or bismuth which would contaminate the purified zinc. However, in such circuits, it would be appropriate and advantageous to use ammonium or sodium persulfate as oxidants, since ammonium or sodium ions and the sulfate radical can later be used in the Jarosite formation step to remove iron from the extraction fluids. Descriptive oxidizing agents include ammonium persulfate, sodium persulfate, potassium persulfate, sodium bromate, sodium bismuthate and lead dioxide. Of these, ammonium and sodium persulfates are preferred oxidants due to their easy availability, ease of handling and preparation, their lack of precipitation of the metal to be recovered and more specifically because, as mentioned above, these persulfates have the advantage of being further used to remove iron from liquids for zinc recovery. in the ‘JJarosite process’ of the electrolytic process referred to in

It is essential for the successful removal of insoluble manganese ions from zinc-containing solutions that substantially no co-precipitation of zinc metal with manganese dioxide occurs, as such co-precipitation results in unacceptable and uneconomical loss of valuable zinc metal. In this regard, although the exact theory is not fully understood, it has been found that when zinc co-precipitates with manganese, a precipitate consisting mainly of hydrated manganese (2) -manganite, ZnO-MnCl 2 - 2-4h 2 O, containing chemically bound zinc results. In addition, it has been found that such hydrated manganese (2) manganite is formed in large amounts when the oxidant is used in an amount well in excess of about 150% of the theoretical amount required for substantially complete manganese removal and that under these conditions hydrated magnesium (2) manganite contains significant amount of zinc, approximately 8-9% as an obvious chemical substitute for manganese. Under such conditions, vigorous washing of the precipitate does not affect the amount of zinc co-precipitated with manganese.

It has also been found that when the oxidant is used in an amount less than about 150% of the theoretical amount required for substantially complete manganese removal, the resulting crystalline phase precipitate contains substantially less hydrated manganese! 2) -manganite and in fact gamma-manganese dioxide γΜη02 becomes the predominant phase , which coincidentally is economically desirable for use in the battery industry. Such gamma-manganese dioxide retains minimal or substantially no zinc. Thus, it is found essential to the successful operation of the claimed invention that the precipitate be in substantially crystalline form of gamma-manganese dioxide in order to substantially exclude the zinc-binding manganese (2) manganite.

5,65815

The identification of the crystalline phases of hydrated manganese (2) manganites and gamma-manganese dioxide as a function of the amount of oxidant used is confirmed by X-ray diffraction images of the precipitates (oven dried below 37 ° C) which show significant variations in crystallinity and phase composition under oxidation conditions. With higher oxidation, i.e. when the oxidant is above about 150%, manganese (2) manganites are formed which have X-ray diffraction patterns similar to those of 6MnO 2 and are represented in nature by the mineral birnesite corresponding to the formula (NaQ j) Mn ^ 0 ^^ 2.8 ^ 0. Numerous metal ions, including zinc, are reported to be bound to similar modifications of this mineral phase. (Peitknecht, W.P. and Marti, W. (1945a), "Uber die Oxidation of Manganese Hydroxyd with Molecular Sauerstoff",

Helv. Chim. Acta, Vol 28, pages 129-148; Peitknecht, W.P. and Marti, W (1945b) "Uber Manganit und Kunstlichen Braunstein", Helv. Chim.

Acta, Vol. 28, pages 148-156; Buser, W. Graff, P. and Peitknecht, W. (1954), "Beitrag zur Kenntnis der Mangan (II) -Manganit und des 6MnO2" Helv. Chim. Acta, Vol. 37, pages 2322-2333; Jones, L.H.P. and Milne, A.A., (1956), "Birnessite, a New Manganese Oxide Mineral from Aberdeenshire Scotland", Mineral. Mag. Vol. 31, pp. 283-288).

In less oxidized fines, i. when the oxidant is less than about 150%, additional lines appear at X-ray diffraction images at 2.12, 1.63, and 4.04 Å, indicating a new crystalline phase or a change in the manganese (2) -manganite phase. The X-ray diffraction results cast doubt on the progressive phase change to the less hydrated form of MnO 2 (primary γΜη02). This was later confirmed by precipitating larger amounts of yMnO 2 under lower oxidation conditions. Under such lower oxidation conditions, brownish-black precipitates are formed which contain minor amounts of zinc (1-2% Zn) and whose X-ray diffraction patterns do not resemble those of birnesite and other manganite phases, but closely correlate with those of MnO 2.

When smaller amounts of oxidant are used, a manganese precipitate determined by X-ray diffraction analysis to be gamma-type crystalline manganese dioxide is believed to form according to the following chemical reaction:

MnSOjj + (NHi |) 2S20g + 2H20—> γΜη02 + (NH ^ SO ^ + 2H2S01 |

Reaction I

6 65815

When larger amounts of oxidants are used, the zinc-manganese complex formed, which has been identified by X-ray diffraction analysis as zinc-containing manganese (2) -manganite, is believed to consist of the following reaction: + 6 (NHi |) 2S20Q + 15H2O + ZnSO2 -> ZnO (NHi |) 2SOi <+ 13 ^ 30 ^

Reaction II

Not only is the production of substantially zinc-free gamma-manganese dioxide essential for the successful operation of a commercially viable manganese removal process, but it is also essential that the resulting precipitate be easily filterable to allow easy separation of the precipitate from solution. In this regard, it has been found that despite the requirement that less than about 150% of the oxidant be used to minimize co-precipitation of zinc and to ensure that the gamma-manganese dioxide crystal form is predominant when the amount of oxidant used is substantially less than about 130% of the theoretical amount. , which is required for substantially complete removal of manganese, a gamma-manganese dioxide precipitate is obtained, from brown to black in a colloidal state. Such a colloidal precipitate is, of course, not easily filterable and therefore tends to be commercially unsatisfactory.

Not only is poorly filtered colloidal gamma-manganese dioxide precipitate formed under the above low oxidant conditions, but it has also been found that the precipitate formed under these conditions contains varying amounts of zinc sulfate which becomes increasingly difficult to wash off as the relative amount of oxidant is reduced. As is the case with the co-precipitation of zinc metal with a high amount of oxidant application, such a loss of zinc sulphate is also unsatisfactory from an economic and commercial point of view.

Thus, it can be seen that when the amount of oxidant is substantially greater than about 150% of the theoretical amount required for substantially complete manganese removal, the precipitate, although having good filterability, nevertheless is in the manganese (2) manganite crystal form, with a significant amount of zinc metal. coprecipitates. When the oxidant is substantially less than about 130%, a precipitate is formed which, although substantially in the form of a gamma-manganese dioxide crystal and substantially free of co-precipitated zinc metal, is not easily filterable.

Thus, a characteristic feature of the present invention is that the oxidant is present in an amount of about 130-150% of the theoretical amount required for substantially complete removal of manganese as gamma-manganese dioxide, and it is preferred that the oxidant be between about 130- 140% amount.

The oxidation reaction can be carried out at temperatures ranging from about 90 ° C to the boiling temperature. In actual plant practice, it would be wise to keep the temperature below the boiling point.

Reaction times can be as short as about 30 minutes and are preferably about two hours.

Oxidation is recommended to be performed at normal pressure, eliminating the need for pressure equipment such as autoclaves, although pressures higher than normal pressure may be used if desired.

Finally, there is the question of the hydrogen ion concentration of the solution. A wide pH range is suitable, but it is recommended to keep the pH between about 5-12. It has been found that solutions that are highly acidic tend to degrade persulfate-type oxidants and that, as a result, more oxidant must be used to overcome this loss to achieve maximum manganese precipitation.

Within the parameters described above, it will be appreciated that such factors, however, may vary the amount of oxidant, reaction time, reaction temperature and pH of the solution to obtain the desired optimum recovery for the metal-containing solution in question. The conditions mentioned above are most suitable for zinc sulphate solutions, especially when zinc is to be recovered by electrolysis and using the "Jarosite process", and it is obvious that those skilled in the art are required to perform only routine experiments to find the most optimal conditions within these limits. solutions containing other metals such as copper, nickel, cadmium, etc.

The "Jarosite process" is referred to above. This phrase is used herein to refer to a well-known improvement in methods for recovering zinc from electrolytically calcined sulfide concentrates, which improvement relies on highly acidic extraction followed by precipitation of iron using sodium, potassium or ammonium ions prior to electrolytic recovery of zinc 8,65815. A more detailed description can be found in the American edition of "World Mining" from September 1972, pages 26-30.

Referring to the sole drawing sheet, there is shown a conventional electrolytic system for zinc recovery using fractional precipitation as well as manganese removal in accordance with the present invention. Manganese removal minimizes electrolyte fouling, greatly increases the operating time of the electrolytic cell, and keeps the cathode in the highest purity. The process described in the flowchart is self-explanatory with respect to the overall process, but for greater completeness it will be described in more detail.

The zinc sulphide concentrates are conveyed to the feed silos of the roaster and then to the roasters, which are of the most suitable fluidized bed type, where the concentrate is kept at a temperature of about 950 ° C to convert the zinc sulphide in the concentrate to zinc oxide (calcine) and sulfur dioxide gas.

The zinc roast is cooled, ground to 90 5i to 200 mesh and transported to extraction tanks in which zinc oxide and any zinc sulphate present are dissolved using sulfuric acid. To achieve maximum zinc recovery, the extraction can be performed in two or more steps: neutral extraction at a pH of about 4.5-5, followed by separation of the zinc-containing liquid from solids, and one or more hot acid extraction steps in which ammonium sulfate is added to one of the steps.

As the last step of these extraction steps, iron precipitates as a complex ammonium jarosite compound 2NH 2 / Fe 2 (SO 2) 2 (OH) g_7, which is then separated together with other insoluble materials. The recovered liquid containing dissolved zinc sulfate is returned to the first extraction step.

The solution containing dissolved zinc from the first "neutral" extraction step is purified (copper and / or cadmium present is removed by precipitation with zinc dust) and filtered and some of the resulting "pure" solution is subjected to manganese removal with ammonium persulfate as described above and as further described in the following examples. After separation of the manganese dioxide 9,65815, the demanganized solution is returned to a hot acid extraction cycle in which the ammonium ion and sulfate radical contained can be used for fractionation or electrolysis.

The remaining pure solution is transferred to electrolytic cells, where by applying a direct current to it, the acidified zinc sulphate solution is decomposed and metallic zinc is precipitated on the cathode (usually aluminum).

Cathode zinc is removed from the cathode, melted in a furnace such as an electric low frequency induction furnace, and cast into slabs, ingots, or other commercially used forms.

The invention is further illustrated by the following examples, which are given by way of illustration only and are by weight unless otherwise indicated.

Example I

To 50 ml of an acidic zinc sulphate solution containing 40.5 g / l Zn and 4.28 g / l Mn (the complete analysis of which is given in Table I below) obtained from the extraction of roasted zinc sulphide flotation concentrate with dilute sulfuric acid was added approximately 5 g of ammonium persulfate and the pH was adjusted to slightly acidic with ammonium hydroxide.

The solution was boiled for approximately 50 minutes and the resulting precipitate was filtered off and washed with distilled water. The filtrate was analyzed for zinc by volumetric titration and for manganese by atomic absorption.

The demanganized solution was analyzed to contain 35.2 g / l Zn and 0.0026 g / l Mn, indicating a selective removal of 99.94 manganese and only 13.1% zinc removal.

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Example 2

Ammonium persulfate was added to samples of the various solutions shown in Table I and stirred at 90 ° C to boiling temperature at varying temperatures for periods ranging from 15 minutes to 2 hours. The amount of ammonium persulfate added was varied according to the needs of the manganese content, the hydrogen ion concentration, the reaction temperature and time, and other conditions described above.

The precipitate obtained was removed in all cases by filtration and the filter cake was washed with water. The filtrate was analyzed for the various elements shown in Table I and the removal of manganese and other metals was calculated.

As can be seen from Table II, the solutions reacting to the process covered a wide range containing larger amounts of manganese and metals such as zinc, copper, nickel, cobalt, cadmium, and iron. Solutions containing only one or more of the metals were found to be equally sensitive to the process.

Manganese was selectively removed from these solutions in the presence of only small amounts of other metals in the manganese precipitate.

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Example 3

Samples of the neutral zinc sulphate solution containing 116.3 g / l Zn and 5.24 g / l Mn (see Table I for complete analysis) were kept boiling for about 15 minutes by adding various oxidants 100 g / l to the solutions: n amounts. The solutions were filtered and the filter cake was washed with water and the filtrate was analyzed for manganese.

The results are shown in Table III and clearly show almost complete removal of manganese in all cases.

The oxidants used were ammonium peroxide sulfate (NH 3) 2 ^ 203 »sodium peroxide sulfate (Na) 2 S 2 O 2, potassium peroxide sulfate K 2 S 2 OQ (also known as persulfates), sodium bismuthate NaBiO 2, sodium bromate NaBrO 2 and lead dioxide P

Table III

Removal of manganese from a neutral zinc sulphate solution (5.24 g / 1 Mn) using different oxidants Oxidant used Demanganized solution Precipitated manganese g / 1 Mn%

Armonium psulfate (NH1i) 2S208 0.0086 99.84

Sodium persulfate (Na) 2 S 2 O 8 0.0024 99.95

Potassium persulfate k2s2o8 0.0095 99.82

sodium bismuthate

NaBiO3 0.016 99.69

sodium bromate

NaBrO 2 0.027 99.96

Lead oxide

Pb02 0.0005 99.99

Example 4

Table IV shows a series of experiments in which samples of a neutral zinc sulphate solution were mixed at 90 ° C for varying times with different amounts of ammonium persulphate. As before, the solutions obtained were filtered and the precipitates were washed with water. In these experiments, however, both filtrates and precipitates were analyzed for zinc and manganese. Zinc and manganese removal could therefore be calculated based on analyzes of both materials.

14 6581 5

As can be seen from the results shown in Table IV, manganese was precipitated from solutions using a wide range of amount of oxidant added, i. between 50-460% of the theoretical amount required to precipitate manganese as manganese dioxide. The following data apply to all experiments summarized in Table IV:

Experiment 10 A

The zinc sulphate solution containing 5.24 g / l Mn was stirred at 90 ° C for 30 minutes with a sufficient amount of ammonium persulfate to compound 460% of the manganese contained therein. The ore slurry was easily filtered, but the precipitate was found to be predominantly manganese (2) -manganite ZnO · 6MnO 2 · 2-4H 2 O, which analysis showed a high zinc content of 8.00%. X-ray diffraction analysis shows that no gamma-manganese dioxide was present and only a small amount of zinc sulfate was found in the precipitate, indicating that most of the zinc was chemically bound to manganese (2) -manganite.

Experiment 11 This experiment was performed as in Experiment 10 A, but the amount of ammonium persulfate used was reduced to 230% of theory. The ore slurry filtered easily, but the precipitate still contained a large amount of zinc, amounting to 9.40% Zn, and consisted mainly of manganese (2) -manganite, in which a small amount of gamma-manganese dioxide began to be present. Zinc sulphate was also present, indicating that part of the zinc contained in the precipitate was due to inefficient washing of the filter cake.

Experiment 12 This experiment was a replicate of Experiment 11 except that the mixture was added for 60 minutes and a thorough washing of the filter cake was performed. The results were similar to Experiment 11 except that the amount of zinc in the precipitate was lower at 5.60% Zn due to the improved filter cake washing technique. Again, the precipitate was predominantly manganese (2) manganite, with some gamma-manganese dioxide present.

Experiment 13 The conditions in this experiment were consistent with those used in Experiment 12 except that the amount of ammonium persulfate used was further reduced to $ 130 of the theoretical requirement for manganese precipitation. The ore slurry filtered easily and the precipitate consisted entirely of gamma-manganese dioxide. No manganese (2) manganite was detected and the precipitate contained only 1.82% Lv. The removal of manganese from the solution rose to 92.65 / &.

15 6581 5

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Experiment 13 was repeated, but the reaction time was extended from 60 minutes to 120 minutes. The ore slurry again filtered very easily and the precipitate consisted of gamma-manganese dioxide with a low zinc content of 1.78 Zn and the removal of manganese from the solution improved to 99.99%.

Experiment P-8 In this experiment, a zinc sulfate solution containing 3.90 g / 1 Mn was used, and ammonium persulfate was added enough to precipitate 133% of the manganese contained in the solution. Stirring was performed at 90 ° C for 2 hours and the ore slurry filtered very easily. The precipitate consisted mainly of gamma-manganese dioxide, but some zinc sulfate was present due to inefficient washing. No manganese (2) manganite was detected.

Experiments D-3, D-4t D-2, D-1 These experiments were performed with the same solution used in Experiments 0-8 and sufficient ammonium persulfate was added to theoretically precipitate 102, 102, 82 and 50% of the manganese in solution, respectively. Filtration became increasingly difficult as the amount of oxidant was reduced; and at 50 # of the theoretical need, the precipitate was so fine that it completely passed the filter paper.

Stirring the solution for a longer time, i.e., 3 hours in Experiment D-4 (102% ammonium persulfate) compared to 2 hours in Experiment D-3, did not improve the filtration situation. As can be seen, the precipitates consisted mainly of gamma-manganese dioxide with varying amounts of zinc sulfate, which became increasingly difficult to wash off as the amount of oxidant was reduced. The manganese dioxide precipitates obtained in these experiments were very fine; while these fine particles had bound to each other in those experiments using 130130% of the theoretical amount of ammonium persulfate, forming agglomerates that resulted in rapid and efficient filtration and enabled efficient washing to remove zinc sulfate.

According to the X-ray diffraction results, the precipitates obtained from Experiment 10 A are consistent with the images reported for birnesite. In less oxidized fines, i. in Experiments 11 and 12, additional lines appear at X-ray diffraction images at 2.12, 1.63, and 4, OA Ä, indicating either a new crystalline form or a variation of the manganese (2) -manganite form. X-ray 16 6581 5 diffraction results cast doubt on the progressive phase change to the less hydrated form of MnCl 2 (primary yMnOg). This was subsequently confirmed by precipitation of mostly yMnCl 2 under milder oxidation conditions, as summarized in Table IV.

Under conditions of milder oxidation (i.e., Experiments 13 and Ib), dark brownish black precipitates are formed containing small amounts of zinc (1-2% Zn). X-ray diffraction images do not resemble birnesite or other forms of manganite at all, but correlate closely with γΜηΟ ^ η images. Precipitates that have not been thoroughly washed contain detectable amounts of ZnSO 4 -HgO, which is present as a crystalline phase in the dried products. This results in relatively high zinc values, as in Experiment No. 11. Smaller amounts of ZnSO 2 HgO were also detected by X-ray diffraction in Experiment No. 10 A.

X-ray diffraction images of different products were developed to show the forms formed under different oxidation conditions. The tabulation of the 10 A-1b '^ "intervals of Experiments 10 is compared between the different forms in Table IV A.

The pellets from Experiments 10A-1b were then heated for up to one hour at 200 ° C and 450 ° C to assess stability phase changes for identification.

Dehydration at 200 ° C only resulted in a collapse of the main gap near 7.0-7.4 Angstroms, apparently as a result of the removal of deposited water.

At 450 ° C decomposition occurs, resulting in mixtures of mostly hydrohetaerolite HZnMngO 2 and γΜηΟ ^. Samples containing higher amounts of structural zinc are converted to a greater extent to hydrohetaerolite (Experiment 10 A), while unwashed ZnSO 4 -f 2 O is simply converted to anhydrous ZnSO 4 without binding to manganese oxide (Experiment 11).

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Example 5

Removal of manganese from the solution was found to be possible in the temperature range from ambient to boiling temperature, as shown in Table V. However, at lower temperatures, the reaction rate was low. At 90 ° C, a reaction time of 2 hours and 135% Ha of the theoretical oxidant requirements, 99.99% of the manganese precipitated from the purified zinc sulphate solution in Experiment 16. At 70 ° C, 50 ° C and 25 ° C with the same amount of oxidant and the same reaction time in experiments 17, 18, and 19, the amount of manganese precipitated was only 22.66%, 13.48%, and 8.24%, respectively. By extending the reaction time at 25 ° C (ambient temperature) to 24 hours in Experiment 20, manganese removal increased somewhat to 14.61 JS.

Table V

Removal of manganese from purified zinc sulphate solution (5.34 g / 1 Mn) at different temperatures

Experiment Time Temperature Demanganized Removed manganese: n hours ° C solution, g / l Mn% 16 2 90 0.0006 99.99 17 2 70 4.13 22.66 13 2 50 4.62 13.48 19 2 25 4.90 8.24 20 24 25 4.56 14.6l

Example 6

Experiments performed at 90 ° C with a large excess of oxidant showed that a relatively short reaction time could be used, as shown in Table IV. With 460 # of the theoretical amount of oxidant, 99.84% of the manganese could be removed from the solution in 30 minutes, as shown in Experiment 10 A. However, at $ 130 of the theoretical amount of oxidant, a reaction time of 2 hours was required to achieve this degree of manganese removal, as can be seen from Experiments 13 and 14. Example 6 has shown that the temperature of the solution is an important factor when considering the reaction time.

The economics associated with the detrimental features of contamination of manganese precipitate with other elements and the type and size of the precipitation equipment dictate the optimum reaction time of the process in industrial use.

20 6581 5

Table VI

Removal of manganese from a neutral zinc sulphate solution (5.24 g / 1 Mn) at different reaction times

Experiment Time (NHjJpSpOg- Demanganized% Manganese No. min *, solution g / 1 Mn removed h υθΟΓ «10 A 30 130 0.0086 99.84 13 60 130 0.385 92.65 14 120 130 <" 0.0002 99, 99

Example 7

Solutions that are highly acidic appear to degrade persulfate-type oxidants and more oxidant must be used to overcome this loss and achieve maximum manganese precipitation.

As shown in Table I, the acidic zinc sulfate and neutral zinc sulfate solutions contained similar amounts of manganese, i.

4.28 g / l Mn and 5.24 g / l Mn, but the hydrogen ion concentration was very different because the acidic solution contained 103.6 g / l L 2 SO 4, while the pH of the neutral solution was 5.3.

Both solutions were treated with $ 130 of the theoretical amount of oxidant required to precipitate all manganese for 2 hours at 90 ° C. As can be seen from Experiments 14 and 21 in Table VII, 99.99% of the manganese was removed from the neutral solution, while only 35.51% was removed from the acidic solution. When the amount of oxidant was increased to 400% in the theoretical experiment 22 in connection with the acidic zinc sulphate solution, considerably more manganese was removed, i.

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Therefore, it can be concluded that this process operates over a wide range of hydrogen ion concentrations in solution, but the recommended pH would be close to neutral to alkaline, i. pH 5-12, 6581 5 21 cd

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The experiment was performed under the recommended conditions mentioned in the other examples, i. ammonium persulfate as oxidant - 135% of the theoretical amount required to precipitate manganese according to reaction I - at 90 ° C for two hours - using a purified zinc sulphate solution with a pH of 5.

The details of the experimental conditions were as follows: 30 g of ammonium persulfate was stirred in 1 liter of purified zinc solution for 2 hours at 90 ° C. The ore slurry was filtered and the filter cake was washed to give 1 liter of demanganized solution. The cake was reslurried and refiltered 3 times with 1 liter of water. Resuspension was performed with stirring for 30 minutes at 70 ° C. The precipitate was dried at 93 ° C overnight.

As can be seen from Table VIII, 99.97% of the manganese was removed from the solution along with only 0.16% of zinc. The manganese dioxide precipitate was of the gamma crystal type and contained 61.0% Mn and 2 l Zn by analysis with very small amounts of all other elements.

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6581 5

Although the invention has been described in connection with a preferred embodiment, the invention is not intended to be limited to the form specifically set forth, but rather to encompass such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

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Claims (2)

6581 5 25 1. A feedstock for the production of manganese from the solution of zinc sulphate, the addition of a mixture of manure or oxide rings with a solution of oxide and a mixture of oxide and a mixture of manganese (2) or a solution of this solution the temperature and the temperature of the solution in the manganese (2) are in the form of a solution of gamma-manganese dioxide, the colors of which are in the range of 130-150% of the theoretical value, which is separated from the average of the manganese or the manganese. A process for removing soluble manganese ions from a solution containing zinc sulphate, characterized in that the solution or part of the solution is treated with an oxidizing agent capable of oxidizing soluble manganese2) to li-insoluble and filterable to be obtained at least in part as gamma-manganese dioxide, the amount of oxidant being about 130-150% of the theoretical amount required to remove substantially all of the manganese from the solution, and the precipitate is separated from the solution. Process according to Claim 1, characterized in that the temperature is from about 90 ° C to the boiling point of the solution and the time is from about 30 minutes to two hours. Process according to Claim 1, characterized in that the oxidant is ammonium persulphate, sodium persulphate, potassium persulphate, sodium bismuthate, sodium bromate, lead oxide or a mixture thereof. Process according to Claim 3, characterized in that the oxidant is ammonium persulphate, the reaction time is about 2 hours and the temperature is about 90 ° C. 2. The first step of step 1 is to maintain the temperature at a temperature of about 90 ° C and at a total temperature of about 30 minutes and then dim.