JPS60197828A - Treatment of pyrite cinder - Google Patents

Abstract

PURPOSE:To make pyrite cinder contg. Cu, Zn, Pb, As, etc. reusable as an iron source by treating said pyrite cinder with an aq. mineral acid soln. contg. iron salt and dissolving and extracting the above-mentioned impurities and to reutilize the residual liquid for treating the pyrite cinder by precipitating the impurities in the extracting liquid. CONSTITUTION:The pyrite cinder after SO2 of raw material for sulfuric acid is drawn by combustion of sulfide iron ore contains Cu, Zn, Pb, As, etc. as impurities and are not usable as a raw material for iron making. The impurities such as Cu, etc. are consequently dissolved and extracted by adding an aq. soln. of HCl and H2SO4 contg. iron salt such as FeCl2, FeSO4, etc. at 20-100g/l in terms of Fe and having <=1pH to said pyrite cinder at 5-10m<3> for each one ton of the pyrite cinder and treating the same for <=60min. The treated pyrite cinder is subjected to a solid-liquid sepn. and the cinder from which Cu, etc. are removed is used as the raw material for iron making. The liquid is treated by H2S, etc. to settle Cu, As as sulfide. The remaining liquid is reutilized for treating the pyrite cinder. Part thereof is fed to a stage for removing Zn, Pb, etc. failing to settle and is thus regenerated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sulfuric acid sintered ore having a low content of non-ferrous metals such as copper, zinc, lead, etc. and arsenic from sulfuric acid sintered ore containing various elements such as arsenic.

Sulfuric acid sintered ore (hereinafter referred to as sintered ore) cannot be used as a raw material for iron manufacturing without pretreatment because it contains nonferrous metals such as copper, zinc, and lead, and arsenic. As a pre-treatment method for removing the above-mentioned elements from burnt ore, the following methods are well known.

The first method is to add a solution of calcium chloride to burnt ore to form agglomerates, and to burn the agglomerates at a high temperature to volatilize C chloride, thereby removing the above-mentioned elements in the burning gas. Although this method is described in Japanese Patent Publication No. 44-7827 and is excellent in practical terms, it is not possible to remove arsenic if it is contained in the burned ore. Even if arsenic is not included in the non-ferrous metals, removal of these metals is insufficient if the content of the non-ferrous metals is large. Are listed. Therefore, this method is not practical when C1 burnt ore contains arsenic or a large amount of non-ferrous metals.
In order to perform M, further preprocessing is required.

A second known method is to treat the burned ore in a fluidized bed or rotary kiln with a high temperature reducing gas to remove arsenic in the gas. This method is
-18802, 49-12807, 49-3760
This is the method described in No. 3, etc., but in both cases the temperature is 1000°C.
This method is economically disadvantageous because it requires relatively high temperatures, cannot remove non-ferrous metals other than arsenic, and requires sufficient heat recovery from the high-temperature gas containing arsenic.

The third well-known method is to mix burnt ore with carbonaceous fuel, and while maintaining this mixture at a high temperature due to combustion of the carbonaceous fuel in a fluidized bed, chlorine gas is blown into the mixture to simultaneously remove nonferrous metals and arsenic from the gas. This is a method of covering it. This method is described in Japanese Patent Publication No. 50-25414, but in addition to requiring high temperatures similar to the above method, since the gas contains chlorine, chlorine and arsenic are removed from the gas containing chlorine and arsenic. It is difficult to recover a sufficient amount of carbon dioxide, and like the above method, this method is economically disadvantageous.

Unlike the conventional methods described above, which are all dry methods that use high temperatures, this invention method involves immersing burnt ore in a strongly acidic leachate described below to extract nonferrous metals and arsenic into the leachate. This is a new wet sintering method. In the burning ore treatment method according to the present invention, the burning ore is immersed in a strongly acidic mineral acid solution having a Pl-1 value of 1 or less and containing metals as chlorides or sulfates, and the burning ore is leached out during this immersion. The non-ferrous metals and arsenic in the burnt ore are extracted into the liquid.The second step is to separate the extracted burnt ore and the leachate.After the extracted burnt ore has been separated, the leachate contains sulfur. A third step in which a sulfiding agent is added, and a fourth step in which solids present in the leachate to which the sulfurizing agent has been added are removed, and most of this liquid is recycled to the first step. This is a processing method.

This invention will be explained in detail below. Water is used as a solvent for the leachate used for leaching the burnt ore in the first step, and in this water I) mineral acids such as hydrochloric acid and sulfuric acid in an amount such that the l-1 value is 1 or less, and several types of It is an aqueous liquid containing metal chlorides or sulfates. Among the substances to be contained in these leachates, the mineral acids are preferably hydrochloric acid, sulfuric acid, or a mixed acid of both. Generally, when only hydrochloric acid is used, the dissolution rate of iron in the burnt ore is high, and when only sulfuric acid is used, the extraction rate of lead in the burnt ore is low. This will slightly reduce the effect of Therefore, the best extraction effect can be obtained when a mixture of hydrochloric acid and sulfuric acid is used. The concentration of these acids is 50 to IL') OQ as free hydrogen chloride if only acid is used.
It is good to be within the range of r/J. In addition, when using IA acid or mixed acid, the 1 temperature acid depth l) l-
It is sufficient to mix sulfuric acid in an amount equivalent to 1 bean paste. If the acid concentration is lower than the above range III, the extraction rate of non-ferrous metals will decrease, and if the acid concentration is higher than the above range, the dissolved M rate of iron will increase and leachate will be generated. The thermal pressure of the acidic gas increases, so it is to your advantage to avoid it. The metal chlorides or sulfates that should be present in the leachate include ferrous chloride,
Chlorides or sulfates of several metals, mainly ferrous sulfate and TFI compounds of both, all of which promote the extraction of nonferrous metals and arsenic from burnt ore into leachate. There is a b in order to exert the M effect, that is, the so-called salt effect. Among these metal salts, ferrous salt is the most important.
The leachate containing J has an excellent effect on the extraction of non-ferrous metals and arsenic.

If the concentration of ferrous salt is below the above range, the effect of salts such as ferrous salt in this leaching will be insufficient and the extraction rate of nonferrous metals and arsenic will decrease; The use of ferrous salt concentrations does not improve the extraction rate and is wasteful.

Among these metal salts, those other than iron do not require a temperature of tfU, and exist in the leachate in a dissolved or suspended state at 9 degrees Celsius when extracted from the burnt ore. However, iron salts among these metal salts are usually leached and extracted from burnt ore and can maintain the above temperature, but the temperature of this iron salt is outside the above range.
In this case, it is recommended to adjust the concentration by supplementing or removing iron salts. Also, the temperature during leaching is 50~
The temperature is preferably 80°C, preferably 60 to 70°C, and there is no need to increase the pressure. In addition, the M ratio of burnt ore to leachate in this leaching culm varies depending on the particle size distribution of the burnt ore and the type of equipment used for leaching, but it depends on the amount of leachate per ton of burnt ore. If the required amount is in the range of approximately 5 to 10% (C), if this ratio is smaller than the above range, the extraction of non-ferrous gold and arsenic will not be sufficient, and the
If J Iflt becomes high, it becomes difficult to handle the slurry with a pump, etc., and conversely, if this ratio is higher than the above range, there will be a lot of waste. The time required for leaching is
? 'j; Within 60 minutes, in most cases 15 to 30 minutes C is sufficient. The time, amount of leachate used per burnt ore, etc. are determined by the type of sulfide ore that is the raw material ore for the burnt ore.
3 and the firing conditions when roasting the sulfide ore, so it is best to make a decision after conducting tests on the burnt ore that will actually be used. Furthermore, the particle size distribution of the burned ore used in the method of this invention may be the particle size distribution of the burned ore obtained by roasting 1q of crushed sulfide ore, which is the raw material for this burned ore, under normal conditions; There is no need to go.

A specific method for carrying out the first step above is to distribute a mixed slurry of burnt ore and leachate in a concrete, carbon steel, or other metal container with an acid-resistant coating on the inner surface. It's better to force it. At this time, in order to prevent the burning ore from settling and separating from the leachate, at least one stirrer is installed deep in the liquid phase, and at least two stirrers are installed to regulate the flow path of the mixed liquid in this container. It is recommended that the walls of the vessel be re-installed and that equipment be installed so that the mixed slurry flows at a relatively high speed within the vessel.

The second step is a step of separating the coexistence of the burnt ore and the leachate from which nonferrous metals and arsenic have been extracted in the first step into the extracted burnt ore and the leachate.

In this step, there is no need to change the temperature from the temperature during leaching, and it is only necessary to separate the solid and liquid.

At that time, once the leachate has been separated, the burnt ore is poured with a small amount of water.
It is best to wash the burnt ore once or twice to sufficiently remove the acid content in the burnt ore. The total amount of water used for this washing is preferably controlled to a level that allows the burned ore, which is usually supplied as a raw material in a dry state, to be contained between the particles. By controlling the washing water m in this manner, it is possible to prevent the concentration of the leachate from decreasing, which would otherwise occur due to the transfer of this water to the leachate, even though the separated burned ore is washed with water. A well-known solid-liquid separation M device can be used for this fraction, but since the amounts of burnt ore A3 and leachate are both large, devices such as so-called drum filters and belt filters are preferred.

Through the first and second steps described above, at least two-thirds of the -C nonferrous metals and arsenic contained in the raw material burnt ore are extracted into the leachate. Although it is possible to further improve the extraction rate by extending the leaching time, the improvement in the extraction rate is small as the equipment becomes larger, and this is often not economically advantageous. The hydrous sintered ore produced from the second step through the above treatment can be used directly as raw material ore for iron manufacturing in many cases, but if the sintered ore contains a large amount of non-ferrous metals and arsenic, Alternatively, the hydrous sintered ore separated as described above can be reprocessed by the first conventional method, that is, the chloride volatilization method. The reprocessing by this chloride volatilization method will be described later.

The third and fourth steps are processing steps for treating the leachate separated in the third step and recycling it to the first step. That is, this step is a step to prevent the temperature of the nonferrous metal and arsenic in the liquid from increasing more than necessary due to repeated use of the leachate. In this third step, a sulfiding agent is added to the leachate separated in the second step to precipitate copper and arsenic contained in the leachate as sulfides. As the sulfurizing agent used in this step, hydrogen sulfide, pyrrhotite, etc. are preferable. As a sulfurizing agent in this process - C,riI! The use of sodium chloride and sodium bisulfide is undesirable because it results in the accumulation of sodium in the circulating leachate. The amount of these sulfiding agents added is the amount necessary to precipitate all m of copper and arsenic present in this leachate as sulfide, and the amount necessary to precipitate all m of copper and arsenic present in this leachate as sulfide, and 3 m of the iron extracted from the burnt ore into the leachate in the first step. The sum of the amount necessary to reduce what exists as valent iron to divalent iron is 11 ffl. When hydrogen sulfide is used as the sulfurizing agent, a well-known gas-liquid contacting device can be used to add hydrogen sulfide to the liquid, and when C pyrrhotite is used as the sulfurizing agent, crushed pyrrhotite can be used. By introducing iron ore into this liquid and stirring it, the sulfidation reaction can be completed in a very short time in either case. In this sulfurization reaction, there is no need to change the temperature of the liquid from the temperature in the first step.

In the 41st step, the precipitates of copper and arsenic sulfides produced in the sulfurization reaction in the third step and other solids present in the liquid are separated from the liquid by a well-known solid-liquid separator. After the substances have been separated, most of the liquid is recycled to the first step as a leaching liquid, and the remainder is used to remove and recover metals such as zinc, lead, and iron that have not precipitated in the third step. Therefore, from the leachate circulation system, there is -1 culm of C. It varies greatly depending on the scale and the dissolution of the tass determined by the leaching conditions.
In most cases, it is on the order of 150 to 250) per ton of burnt ore. This process is simple and can be easily understood by those skilled in the art, so a detailed explanation will be omitted.

The above is the main process of this invention. A part of the circulating leachate extracted from the leachate circulation system as described above is usually made of calcium carbonate, calcium oxide, etc. in order to recover the metals contained in this liquid. In the initial stage of neutralization, the gypsum is precipitated and collected, and the gypsum is separated and recovered. Neutralization is further advanced to precipitate the metal hydroxides, and these are separated and recovered. The TLI solution is then discharged. Alternatively, it can be treated by neutralizing with an alkali such as caustic soda or RW soda, collecting the metal hydroxide precipitate produced during the neutralization, and then discharging the remaining liquid. In addition, to remove the waste in the circulating leachate that occurs when a part of the leachate is withdrawn from the circulation system, the circulating leachate is adjusted to the f [12 concentration of ! !
! Just do it. In addition, from the precipitate made of copper sulfide and arsenic sulfide obtained in the third step and the precipitate of hydroxide, which is made of metals such as zinc, lead, iron, etc. and does not contain copper and arsenic, obtained from the extracted leachate, These metals and arsenic can be recovered by conventionally known methods.

The first advantage of this invention is that unlike the conventional method described above, high temperatures are not used, so thermal energy consumption is extremely low, no waste gas is generated, and the equipment is simple, making the overall treatment cost low. It's a matter of course. This point is quite clear from the above explanation and does not require any special explanation. The second advantage of this invention is that the arsenic compound can be obtained in a state that is easy to isolate. As is well known, when arsenic is mixed with other substances, it deteriorates the properties of the substance, and it also exhibits strong toxicity to many living organisms, so it is impossible to release it into the natural environment. In the method of this invention, the precipitate consisting only of copper sulfide and arsenic sulfide can be separated in the third step as described above. Therefore, for example, as described in Japanese Patent Publication No. 58-24378, the separated precipitate is suspended in water, copper sulfate is added to this suspension to convert arsenic sulfide to arsenic oxide, and the arsenic is dissolved in C water. Copper and arsenic can be easily and almost completely separated by isolation from copper, or by oxidizing the separated precipitate at a relatively low temperature to convert it into copper oxide and arsenous acid, and then subjecting both to a high-temperature sublimation operation. It is possible to do 1m. The third advantage of the present invention is that when burnt ore contains both nonferrous metals and arsenic, the method of the present invention can be used as a pretreatment method for carrying out the first and second conventional methods. It is possible to use it. That is, in the first conventional method, arsenic cannot be removed from burnt ore, and in the conventional method of text box 2, non-ferrous metals other than arsenic cannot be removed. If the method of the present invention is used as a pretreatment for implementing both of these conventional methods, the drawbacks of these two conventional methods can be overcome at low cost. That is, there is no need to use an expensive method such as the third conventional method. Furthermore, as described above, even when the method of the present invention is used as a pretreatment method for the conventional method, it is particularly advantageous when used as a pretreatment method for the first conventional method. This will be explained below.

There are many embodiments of this invention. Many of these embodiments use a combination of known methods for treating burnt ore and the method of the invention, for example, as a pretreatment method for the first conventional method, ie, the chloride volatilization method. We will explain when to use it. As described in the above-mentioned literature, this conventional method involves mixing calcined ore with a calcium chloride solution to form agglomerates, heating the agglomerates in an oxidizing high-temperature atmosphere caused by combustion of fuel, and converting non-ferrous metals in the ore into chlorides. This method removes it from the combustion gas. Therefore, the combustion gas produced by this method contains chlorides of nonferrous metals, sulfur dioxide, and sulfur trioxide.

In the processing of such extremely cheap burned ore, it is not possible to use high-priced m-sulfurized fuel for economic reasons. It is not preferable to collect only non-ferrous metals and release combustion gas containing a lot of sulfur oxides into the atmosphere. Follow-C
1. It becomes necessary to remove and recover non-ferrous metals and sulfur oxides from this combustion gas. The advantage of using the method of this invention as a pretreatment for the chloride volatilization method is that even if arsenic, which cannot be removed by the chloride volatilization method, is contained in burnt ore, it can be removed by the method of the present invention, and as described above. In the fourth step, a part of the leachate is extracted from the circulation system, and this extracted liquid is neutralized with a calcium compound,
The calcium chloride-containing effluent after sulfate ions are recovered as gypsum and nonferrous metals as hydroxides can be used as a calcium chloride solution for agglomerating burned ore in the chloride volatilization method. That is, by reusing this calcium chloride solution, loss of chloride ions can be prevented.

That is, if the above-mentioned effluent is used as a calcium chloride solution for agglomeration of burned ore, and the agglomerates containing calcium chloride are heated and covered by burning fuel as described above, the calcium chloride will be absorbed into the silicon dioxide in the burnt ore. In the presence of metal, it decomposes into chlorine, and most of this chlorine combines with non-ferrous metals and is contained in the combustion gas as non-ferrous metal chloride vapor. At the same time, a portion of the chlorine reacts with water vapor generated as the fuel burns to form hydrogen chloride gas. When this combustion gas is washed with water, hydrogen chloride, chlorides of nonferrous metals, sulfur trioxide, and a portion of sulfur dioxide all migrate into the washing water. Therefore, while cleaning the combustion gas in a state in which the traces of hydrogen chloride and sulfuric acid in the cleaning solution are increased to the concentration of the above-mentioned leachate, a part of this washing solution is extracted and pumped out, and the above-mentioned leachate circulation system is If the cleaning solution is supplied as a replenishment solution, there will be no need to newly prepare hydrochloric acid and sulfuric acid as described above and produce a replenishment solution.Also, the non-ferrous metals contained in the cleaning solution extracted as this replenishment solution will be , together with the non-ferrous metal extracted in the first step of this invention, it will be recovered in the treatment step of the leachate extracted in the third or fourth step of this invention. Therefore, the use of this invention method as a pretreatment method for the chloride volatilization method is very advantageous in terms of cyclical use of materials.
This is also an economically superior method.

As mentioned above, the present invention is excellent as a method for removing arsenic and nonferrous metals from burnt ore containing both arsenic and nonferrous metals, and is particularly suitable as a method for treating burnt ore containing large amounts of arsenic and nonferrous metals. be.

Example 1 500ν! In a separable flask, copper 0.18, zinc 37.9, lead 1.7, divalent iron 54.8, hydrogen chloride 54
．． Strongly acidic leachate containing 7 and 100% sulfuric acid 499"/J 200 xi and 0.36 xi of copper, 0.80 of zinc, 0.105 of lead, 0.154 of arsenic, 48.9 of iron and 14.9 of silicon dioxide 30 gr of sulfuric acid burnt ore from the Soviet Union, 45% of which had a particle size of 44 microns or less in each weight percent, was added and leached at 75° C. with stirring for 30 minutes.

After leaching, the contents of the flask were taken out and separated into solid and liquid into burnt ore and leachate, and each was analyzed. As a result, the leachate contained 0.63 copper, 38°8 zinc, 1.8 lead, and 0.18 arsenic. and iron 64.9 gr/J each, the burnt ore contains 0.07 copper, 0.201 zinc, 0.067 lead, and 0 arsenic.
．． It contained 0.043% and 50.8% iron.

Next, in order to separate copper and arsenic from the leachate after the above-mentioned leaching treatment, 100yf of this liquid was collected in a beaker, and 1.6C1r of ferrous sulfide powder with a purity of 75% by weight or more was added, and the mixture was heated at 60°C. When the mixture was reacted with stirring for 30 minutes, a blackish brown precipitate was produced. Analysis of copper and arsenic in the filtrate after separating and removing this blackish brown precipitate revealed that both copper and arsenic were in very small amounts, less than 1 Tl 1 g/J.

On the other hand, the separated precipitate was washed with water, dried, and weighed.
62 mg, 11.2% copper and 3.2% arsenic by weight
It included.

Furthermore, in order to test the removal of non-ferrous metals from the leached sintered ore by the chloride volatilization method, the leached sintered ore was pulverized until the particle size of 44 microns or less was 80% by weight, and then the powder was crushed. 2% by weight of powdered calcium hydroxide and 4% by weight of calcium chloride solution at 0.59r/if
were added and kneaded, and further granulated into spheres with a particle size of about 15+mm. After drying this granulated product at 150° C., it was fired in a horizontal tubular electric furnace while flowing a mixed gas consisting of 5 mol % of oxygen and 95 mol % of nitrogen containing 609 r of water vapor per 1 kQ of dry residue. Firing at 600℃
The test was carried out by heating the temperature from 1,200°C to 1,200°C for 4 times in 80 minutes, and then holding the temperature at 1,200°C for 15 minutes. Next, the fired granulated product was taken out, cooled, and pulverized for analysis. As a result of the analysis, the burnt ore after the above chloride volatilization treatment contained 0.02 copper,
Zinc 0.013, lead o, oi, arsenic 0.04 and iron 5
The purpose of removing non-ferrous metals and arsenic from raw sintered ore was achieved.

Example 2 In a 500 xl separable flask, 200 g of a strong acidic leachate containing 0.18 gr/g of copper, 37.9 g of zinc, 1.7 g of lead, 27.4 g/g of divalent iron, and 73.0 g/g of hydrogen chloride. 28.6 gr of the sulfuric acid burnt ore used in Example 1 were added to the flask, and the leaching treatment was carried out at 60° C. while stirring for 30 minutes.

After leaching, the contents of the flask were taken out and separated into solid and liquid into burnt ore and leachate, and each was analyzed. As a result, the leachate contained 0.55 copper, 38°7 zinc, 1.77 lead, and 0.15 arsenic. The burnt ore contained 0.113% copper, 0.266% zinc, 0.065% lead, 0.056% arsenic and 51.87% iron each rmEU.

Next, in order to separate copper and arsenic from the leachate after the above leaching treatment, 100 xl of this liquid was collected in a beaker and 6
Hydrogen sulfide gas is added to the stirred supernatant liquid at 0°C at a rate of 1 ton per minute.
- React with ventilation for 10 minutes, then 1j for 20 minutes.
When only stirring was continued, a brown precipitate was formed. Analysis of copper and arsenic in the filtrate after separating and removing this brown precipitate revealed that both copper and arsenic were 1111111/
There was a very small amount of C below J. On the other hand, the precipitate was washed with water and dried, and when weighed, it was found to be 370 TIl, containing 14.9% of copper and 4.1% of arsenic.

Furthermore, in order to test the removal of non-ferrous metals from the burnt ore leached above by the chloride volatilization method, granulation and calcination were carried out under the same conditions as in Example 1. Next, take out the fired granulated product,
After cooling, it was crushed and subjected to analysis. As a result of the analysis, the burnt ore after the above chloride volatilization treatment contained 0.025 copper, 0.02 zinc, and 0 lead.
．． 01, arsenic 0.053 and iron 51.9% by weight, and the purpose of removing non-ferrous metals and arsenic from raw sintered ore was achieved.

Claims (1)

[Claims] The sulfuric acid burnt ore is leached with a strongly acidic mineral acid solution that has a P l-1 value of 1 or less and contains -C metals as chlorides or sulfates, and the nonferrous metals and arsenic in the -C sulfuric acid burnt ore are leached into the liquid. The extracted sulfuric acid burnt ore and the liquid are separated, a sulfiding agent is added to the separated liquid, and after the addition, the solids present in the liquid are removed, and the solids are removed. A method for treating sulfuric acid burnt ore, characterized in that a large part of the subsequent liquid is recycled to the leaching.