RU2641826C1 - Method of purifying waste water from molybdenum ions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: treatment is performed with the reagent - waste of production, which is used as iron-containing clay with an iron content of 2 to 20%, or waste of metalworking in the form of chips of non-alloy steel with an iron content of 45 to 85%, pre-treated with sulfuric acid with a concentration of 0.01 to 0.1 N for 0.5 to 1 hours, followed by standing for 16 to 24 hours. The resulting sorption paste or sorbent is introduced into the waste water, continuously mixed for 50 minutes, then left to stand for 3 to 5 hours, and the precipitate is removed.

EFFECT: invention allows with a high degree of the purification to remove molybdenum ions from wastewater using natural materials and wastes with a high iron content.

2 dwg, 9 tbl, 6 ex

Description

The invention relates to methods for chemical wastewater treatment from molybdenum ions using materials with a high iron content.

A known method of wastewater treatment (German patent No. 2610637, publ. 1977), which consists in the chemical deposition of tungsten and molybdenum ions by iron compounds at pH = 2-8 and a temperature of 20-40 ° C. When chemical precipitation is carried out according to the known method, iron sulfate is used in stoichiometric dependence on the concentration of metal ions to be removed, or more often in a 2-3-fold excess, tungsten and molybdenum ions are precipitated in the form of tungstates and molybdenum, and calcium ions are additionally introduced in the form of Ca (OH) ₂ .

The disadvantage of this method is the high consumption of iron sulfate and low cleaning efficiency at low concentrations of pollutants to bring wastewater to the standards of the fishery type of water use.

A known method of producing molybdenum products (AN Zelikman. Molybdenum. - M .: Metallurgy, 1970, p. 150) by mixing solutions of sodium molybdate and Fe ₂ (SO ₄ ) ₃ , followed by precipitation of the molybdenum product at pH 2.5- 3.0, by filtration, washing and calcining the precipitate.

The disadvantage of this method is the low degree of extraction of molybdenum from poor solutions and a high consumption of iron sulfate.

A known method of extracting molybdenum and tungsten during wastewater treatment (US patent No. 4219416, publ. 08.28.1980), which consists in removing heavy metals in their anionic state, in particular, tungsten and molybdenum, when treating wastewater by chemical deposition of heavy metals using gas flotation.

The disadvantage of this method is the low degree of extraction of molybdenum from poor solutions and the need to use a large number of flotation reagents.

A known method of wastewater treatment from heavy metal ions (RF patent No. 2189363, publ. 09/20/2002), which consists in the fact that wastewater treatment from heavy metal ions is carried out by sorption on a solid insoluble natural sorbent, and as a natural sorbent use pyrite enriched up to 84-96%, with a grain size of the sorbent not more than 160 microns.

The disadvantage of this method is the low degree of extraction of molybdenum from poor solutions and the need to use a large amount of pyrite.

A known method of wastewater treatment from heavy metals (copyright certificate SU No. 1263648, published on 10/15/1986), adopted as a prototype, relates to methods for reducing the content of iron and molybdenum in wastewater and consists in treating wastewater with waste from the production of aluminosilicate catalysts of the following composition, wt. %: sodium oxide 5-12; oxide, aluminum 5-10, ammonium oxide 1-4; calcium oxide 1-3; iron oxide 0.5-1.5; cerium oxide 0.5-1.0; silicon oxide rest.

The disadvantage of this method is the low degree of extraction of molybdenum from poor solutions and the need for waste production of limited distribution.

The technical result of the invention is to increase the efficiency of the degree of wastewater treatment from molybdenum ions and the use of natural materials or industrial waste for this.

The technical result is achieved in that a method of treating wastewater from molybdenum ions, including treatment with a reagent — a production waste containing metal oxides, characterized in that iron-containing loam with an iron content of 2 to 20% is used as a production waste containing metal oxides metalworking waste in the form of unalloyed steel shavings with an iron content of 45 to 85%, pre-treated with sulfuric acid with a concentration of from 0.01 to 0.1 N for 0.5 to 1 hours, and settles in those from 16 to 24 hours, and the resulting sorption paste or sorbent is introduced into the wastewater in the ratio TV: W = 1: 100 - 1: 500, constantly stirred for 40 to 60 minutes, followed by settling for 3 to 5 hours and sediment removal.

The method of wastewater treatment from molybdenum ions is illustrated by the following figure:

FIG. 1 - A method of treating wastewater from molybdenum ions.

FIG. 2 - Kinetics of the deposition of iron-bearing loam with an initial concentration in solution of 3 g / DM ³

The method is as follows. The wastewater and the prepared iron-containing sorbent are mixed in the sump in the mixing mode for from 0.5 to 1 hour, followed by sedimentation for 3 to 5 hours. For this, sewage from concentration plants, mine and mine water with a molybdenum concentration of from 0.010 to 1,000 mg / l, a pH of 6 to 8 and a temperature of 15 to 20 ° C are discharged into a sump, then a pre-prepared sorbent in the ratio TV is added to it: W = 1: 100 - 1: 500.

To prepare the sorbent, iron-containing loam with an iron content of 2 to 20% or metal processing waste in the form of unalloyed steel chips with an iron content of 45 to 85%, which is treated with an acid with a concentration of from 0.01 to 0.1 N for a period of 0, is used. 5 to 1 hour, and settles for 16 to 24 hours. The purified and clarified waters are sent to the next stage of treatment (biological), and the sediment is removed from the sump, dehydrated, dried and sent for use in another industrial production.

The course of the wastewater treatment process is explained by the fact that molybdenum sorptively co-precipitates with iron hydroxides and also readily enters Fe ₂ (MoO ₄ ) ₃ with iron, which also contributes to its precipitation. Due to the anionic (at pH> 2–3) form of migration, the sorption precipitation of molybdenum by iron hydroxides mainly proceeds in acidic media (pH = 2–4), which is achieved by acid treatment of the iron-containing material, or by additional acidification of the solution.

The method is illustrated by the following examples. To evaluate the developed technology, mine water samples containing a solution of sodium molybdate Na ₂ MoO ₄ with a molybdenum concentration of 100 μg / l, 500 μg / l and 1000 μg / l were used as model solutions for the experiments.

The hydrochemical characteristics of mine water are presented in table 1.

In examples No. 1, 2, 3, 6, a water sample 1 was used; in example No. 4 used a sample of water 2; in example No. 5 used a sample of water 3.

Example No. 1. As the iron-containing material, we selected iron-bearing loam from the Pervomaiskoye quarry, Leningrad Region, with an iron content of 3%. Loam has undergone acid activation. For this, sulfuric, phosphoric, nitric and hydrochloric acids were selected. Samples of loam of natural moisture (8.9%) were combined with acids of 0.1 normal concentration in the ratio TB: W = 10: 3, the components were mixed for 1 h, and the resulting sorption paste was placed in a desiccator to exclude moisture evaporation and kept for days in order to complete the activation process. In addition, the dependence of the cleaning efficiency on the ratio of loam and acid was studied; for this, samples of loam of natural moisture (8.9%) were combined with sulfuric acid of 0.1 normal concentration in the ratios TV: W = 10: 1; 10: 2; 10: 3; 10: 4; 10: 5; 10:10, the components were mixed for 1 h, and the resulting sorption paste was placed in a desiccator to exclude moisture evaporation and kept for a day in order to complete the activation process. The resulting sorption paste was combined with a model solution of molybdenum with a concentration of 100 μg / L in the ratio TV: W = 1: 100 with stirring for 1 h. A study of the kinetics of sorption showed that the equilibrium in the system in the system occurs after 50 minutes, although the sorption speed is maximum in the first minutes of contact. After settling, the model solution was filtered through 1 layer of a “red ribbon” filter with a pore diameter of ≥10 μm and the concentration was measured on an ICPE-9000 inductively coupled plasma spectrophotometer in an accredited laboratory of the REC of collective use of high-tech equipment of St. Petersburg Mining University. The results are presented in tables 2 and 3.

In addition, in FIG. Figure 2 shows an example of the kinetics of the deposition of iron-bearing loam, where it can be seen that the most intense deposition occurs in the first 4 hours, so the settling time is taken from 3 to 5 hours.

After removal and dewatering, the sludge can be used as a raw material for brick production, since in the course of the studies it was found that molybdenum desorption from the obtained sludge does not occur, moreover, clay loam plasticity is one of its most important properties that determine its suitability for brick production remains virtually unchanged.

As can be seen from table 2, the use of activated iron loam for the purification of model solutions from molybdenum showed high efficiency.

Example No. 2. A standard sample of unalloyed steel shavings (metal processing waste) with an iron content of 72% was taken as the iron-containing material. In order to obtain hydroxide forms of iron with a developed specific surface and increased reactivity, steel samples were wetted with water and weak acid solutions and left in the air for 24 hours (for oxidation processes to occur). Then, the resulting sorbent was combined with model solutions of molybdenum of various concentrations in the ratio TV: W = 1: 500 in the mixing mode for 40 min, the contact time was chosen after studying the sorption kinetics (table 4). After settling, the solution was filtered through 1 layer of a “red ribbon” filter with a pore diameter ≥10 μm and the molybdenum concentration was measured on an ICPE-9000 inductively coupled plasma atomic emission spectrometer in the accredited laboratory of the REC of the collective use of high-tech equipment of St. Petersburg Mining University. The results are shown in tables 3 and 4.

The precipitate formed is a mixture of molybdate and iron hydroxide, so it can be used to produce ammonium paramolybdate. To do this, after removal and dehydration, the precipitate is leached with a solution of ammonia. The resulting solution of ammonium molybdate is processed into ammonium paramolybdate in the usual way.

As can be seen from table 5, the use of hydroxide forms of iron for the purification of model solutions from molybdenum showed high efficiency. Moreover, the use of more concentrated acids as a corrosion activator reduces the cleaning efficiency due to the processes of iron reduction.

Example No. 3. The iron-containing loam from the Kildinsky deposit of the Murmansk region with an iron content of 2% was chosen as the iron-containing material. Loam has undergone acid activation. For this was chosen: sulfuric acid. Samples of loam of natural moisture (7.5%) were combined with acids of 0.01, 0.05, 0.1, 0.5, and 1 normal concentration in the ratio TB: W = 10: 3, the components were mixed for 1 h, and the resulting sorption paste was placed in a desiccator to exclude moisture evaporation and kept for a day in order to complete the activation process. The resulting sorption paste was combined with a model solution of molybdenum with a concentration of 100 μg / L in the ratio TV: W = 1: 100 with stirring for 1 h. After settling, the model solution was filtered through 1 layer of a red ribbon filter with a pore diameter of ≥10 μm and the concentration was measured on an inductively coupled plasma spectrophotometer ICPE-9000 in an accredited laboratory of the REC of the collective use of high-tech equipment of St. Petersburg Mining University. The results are presented in table 6.

After removal and dewatering, the sludge can be used as a raw material for brick production, since in the course of the studies it was found that molybdenum desorption from the obtained sludge does not occur, moreover, clay loam plasticity is one of its most important properties that determine its suitability for brick production remains virtually unchanged.

As can be seen from table 6, the use of activated iron loam for the purification of model solutions from molybdenum showed high efficiency.

Example No. 4. As the iron-containing material, iron-containing loam from the Pechenga deposit of the Murmansk region with an iron content of 20% was selected. Loam has undergone acid activation. For this was chosen: sulfuric acid. Samples of loam of natural moisture (10.1%) were combined with acids of 0.1 normal concentration in the ratio TV: W = 10: 3, the components were mixed for 1 h, and the resulting sorption paste was placed in a desiccator to exclude moisture evaporation and kept for 24 hours in order to complete the activation process. The resulting sorption paste was combined with model solutions of molybdenum with a concentration of 500 μg / l in the ratio TV: W = 1: 100; 1: 200; 1: 300; 1: 400 and 1: 500 with stirring for 1 h. After settling, model solutions were filtered through 1 layer of a red ribbon filter with a pore diameter ≥10 μm and the concentration was measured on an ICPE-9000 inductively coupled plasma spectrophotometer in an accredited laboratory REC collective use of high-tech equipment of St. Petersburg Mining University. The results are presented in table 7.

After removal and dewatering, the sludge can be used as a raw material for brick production, since in the course of the studies it was found that molybdenum desorption from the obtained sludge does not occur, moreover, clay loam plasticity is one of its most important properties that determine its suitability for brick production remains virtually unchanged.

As can be seen from table 7, the use of activated iron loam for the purification of model solutions from molybdenum showed high efficiency.

Example No. 5. As the iron-containing material, a standard sample of unalloyed steel shavings (metal processing waste) with an iron content of 45% was taken. In order to obtain hydroxide forms of iron with a developed specific surface area and increased reactivity, steel samples were wetted with a weak acid solution with a concentration of 0.01 N and left in the air for 24 hours (for oxidation processes to occur). Then, the resulting sorbent was combined with model solutions of molybdenum with a molybdenum concentration of 1000 μg / L in the ratio TV: W = 1: 100; 1: 200; 1: 300; 1: 400 and 1: 500 in the mixing mode for 30 minutes After settling, the solution was filtered through 1 layer of a “red ribbon” filter with a pore diameter of ≥10 μm and the molybdenum concentration was measured on an ICPE-9000 inductively coupled plasma atomic emission spectrometer. The results are shown in table 8.

The precipitate formed is a mixture of molybdate and iron hydroxide, so it can be used to produce ammonium paramolybdate. To do this, after removal and dehydration, the precipitate is leached with a solution of ammonia. The resulting solution of ammonium molybdate is processed into ammonium paramolybdate in the usual way.

As can be seen from table 8, the use of hydroxide forms of iron for the purification of model solutions from molybdenum showed high efficiency.

Example No. 6. A standard sample of unalloyed steel shavings (metal processing waste) with an iron content of 85% was taken as the iron-containing material. In order to obtain hydroxide forms of iron with a developed specific surface and increased reactivity, steel samples were wetted with water and weak acid solutions and left in the air for 24 hours (for oxidation processes to occur). Then, the resulting sorbent was combined with a model solution of molybdenum with a concentration of 100 μg / L in the ratio TV: W = 1: 500 in the mixing mode for 30 min. After settling, the solution was filtered through 1 layer of a “red ribbon” filter with a pore diameter of ≥10 μm and the molybdenum concentration was measured on an ICPE-9000 inductively coupled plasma atomic emission spectrometer. The results are shown in table 9.

The precipitate formed is a mixture of molybdate and iron hydroxide, so it can be used to produce ammonium paramolybdate. To do this, after removal and dehydration, the precipitate is leached with a solution of ammonia. The resulting solution of ammonium molybdate is processed into ammonium paramolybdate in the usual way.

As can be seen from table 9, the use of hydroxide forms of iron for the purification of model solutions from molybdenum showed high efficiency.

Using this method of wastewater treatment allows a high degree (95-99%) to remove molybdenum ions from wastewater using natural materials and waste products with a high iron content.

Claims (1)

A method of treating wastewater from molybdenum ions, comprising treating with a reagent — a production waste containing metal oxides, characterized in that iron-containing loam with an iron content of 2 to 20% or metal processing waste in the form of unalloyed chips is used as a waste from a production containing metal oxides steel with an iron content of from 45 to 85%, pre-treated with sulfuric acid with a concentration of from 0.01 to 0.1 N for 0.5 to 1 hours with sedimentation for 16 to 24 hours, and the resulting sorption The paste or sorbent is introduced into the wastewater in the ratio T: W = 1: 100 - 1: 500, constantly stirred for 40 to 60 minutes, followed by settling for 3 to 5 hours and the sediment removed.

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