Preparation method of arsenic removal agent NP201 for alkaline leaching system

Abstract

The invention discloses a preparation method of an arsenic removal agent NP201 for an alkaline leaching system, and belongs to the technical field of catalyst preparation. The preparation method comprises the following steps: respectively dissolving Ca (NO3) 2.4 H2O and (NH4) 2HPO4 in deionized water to prepare a solution with the concentration of 1-2 mol / L; placing the Ca (NO3) 2 solution in a water bath at 65-75 DEG C, and dropwise adding the (NH4) 2HPO4 solution while stirring; after dropwise adding is completed, the pH value of the reaction system is adjusted to be alkaline, and stirring reaction continues to be conducted for 60-90 min in the water bath at the temperature of 70-80 DEG C; separating a Ca3 (PO4) 2 precipitate obtained by the reaction, washing to be neutral, and adding deionized water to prepare a uniformly dispersed suspension; and then placing in a water bath at 65-70 DEG C, adding 0.5-1 mol / L of a sodium dithiocarbamate solution while stirring, and carrying out chelation reaction for 90-120 minutes. And separating, washing and drying the precipitate obtained by the reaction to obtain the target arsenic removal agent NP201 for the alkaline leaching system. The arsenic removal agent NP201 prepared by adopting the method is high in adsorption capacity, wide in pH application range and high in arsenic removal stability, and the preparation process is simple and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of an arsenic removal agent NP201 for an alkaline leaching system. Background Art

[0002] As a toxic element, arsenic is extremely harmful to the human body and the environment. Under alkaline conditions, arsenic often exists in the form of arsenite (AsO3 3- ) or arsenate (AsO4 3- ). During the alkaline leaching process, arsenic removal is mainly achieved through chemical precipitation, oxidation, or adsorption. However, among the currently widely used types of arsenic removal agents, iron-based arsenic removal agents are sensitive to the pH value. Beyond the appropriate range, the arsenic removal rate will decrease significantly. Especially under strong alkaline conditions, iron-based arsenic removal agents are prone to form colloids, greatly reducing the adsorption efficiency of arsenic, and the generated composite precipitates are difficult to settle, making subsequent solid-liquid separation difficult. Compared with iron-based arsenic removal agents, aluminum-based arsenic removal agents have a weaker adsorption capacity for arsenic, and the usage amount of reagents and treatment costs during treatment increase accordingly. In addition, precise control of the reagent dosage is required during oxidative arsenic removal. If the amount of oxidant added is insufficient, As(III) cannot be completely converted to As(V), which will affect subsequent precipitation. If NaClO is used as the oxidant, toxic by-products will be generated, causing secondary pollution.

[0003] Based on this, the present invention aims to provide a preparation method of an arsenic removal agent NP201 for the alkaline leaching process, expand the applicable pH value range, improve the adsorption efficiency and selectivity, reduce the influence of competing ions, and enhance the solidification and separation effects. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of an arsenic removal agent NP201 for an alkaline leaching system.

[0005] The purpose of the present invention is achieved as follows: The preparation method of the arsenic removal agent NP201 for the alkaline leaching system includes the following steps: Dissolve Ca(NO3)2·4H2O and (NH4)2HPO4 in deionized water respectively to prepare solutions with a concentration of 1 - 2 mol / L; Place the Ca(NO3)2 solution in a water bath at 65 - 75 °C, and while stirring, dropwise add the (NH4)2HPO4 solution; After the dropping is completed, adjust the pH value of the reaction system to alkaline, and continue to stir and react in a water bath at 70 - 80 °C for 60 - 90 min; Separate the obtained Ca3(PO4)2 precipitate, wash it until neutral, add deionized water to make a uniformly dispersed suspension; then place it in a water bath at 65 - 70 °C, and add a sodium dithiocarbamate solution with a concentration of 0.5 - 1 mol / L while stirring, and carry out a chelation reaction for 90 - 120 min; Separate the obtained precipitate, wash it and dry it to obtain the arsenic removal agent NP201 for the target alkaline leaching system.

[0006] Compared with the prior art, the present invention has the following advantages: The arsenic removal agent NP201 prepared by the method of the present invention has abundant Ca on its surface 2+ and PO4 3- , which can undergo electrostatic adsorption and coordination with AsO4 3- , thereby adsorbing AsO4 3- onto the surface of the arsenic removal agent NP201. At the same time, the arsenic removal agent NP201 molecule contains two sulfur atoms, which can form a stable five-membered ring chelate with AsO4 3- , thereby removing AsO4 3- from the solution. In addition, when the arsenic removal agent NP201 is used, it can increase the local concentration, thereby improving the chelation efficiency and arsenic removal stability.

[0007] In summary, the arsenic removal agent NP201 prepared by the described method has good scavenging effects on both arsenate and arsenite. Based on the surface modification effect of sodium dithiocarbamate, the generated composite precipitate can play a synergistic role to improve the arsenic removal efficiency, has a wide applicable pH range, can be used for arsenic removal treatment in complex environments, adsorbs AsO4 3- and enriches it on the surface. After arsenic is fixed, it is not easy to be released again. Specific embodiments

[0008] The following further illustrates the present invention, but does not limit the present invention in any way. Any transformation or replacement based on the teachings of the present invention belongs to the protection scope of the present invention.

[0009] The preparation method of the arsenic removal agent NP201 for the alkaline leaching system includes the following steps: Dissolve Ca(NO3)2·4H2O and (NH4)2HPO4 in deionized water respectively to prepare solutions with a concentration of 1 - 2 mol / L; Place the Ca(NO3)2 solution in a water bath at 65 - 75 °C, and dropwise add the (NH4)2HPO4 solution while stirring; After the dropping is completed, adjust the pH value of the reaction system to alkaline, and continue to stir and react in a water bath at 70 - 80 °C for 60 - 90 min; Separate the Ca3(PO4)2 precipitate obtained from the reaction, wash it until neutral, add deionized water, and prepare a uniformly dispersed suspension; then place it in a water bath at 65 - 70 °C, and while stirring, add a sodium dithiocarbamate solution with a concentration of 0.5 - 1 mol / L, and carry out a chelation reaction for 90 - 120 min; Separate the precipitate obtained from the reaction, wash it, and dry it to obtain the arsenic removal agent NP201 for the target alkaline leaching system.

[0010] When dropping the (NH4)2HPO4 solution into the Ca(NO3)2 solution, the temperature of the water bath is preferably 70 °C.

[0011] The dropping rate is 50 ml / min.

[0012] When dropping, the volume ratio of the Ca(NO3)2 solution to the (NH4)2HPO4 solution is 1 - 2:1.

[0013] The pH value of the reaction system is 10 - 11.

[0014] The alkaline solution used to adjust the pH value of the reaction system can be any one of sodium carbonate, ammonia water, sodium hydroxide, and sodium phosphate.

[0015] When preparing the suspension, the mass - volume ratio of Ca3(PO4)2 to deionized water is 1 - 10 g / 100 ml.

[0016] When preparing the suspension, the ultrasonic dispersion method is used, preferably probe ultrasonic, with a power of 100 - 500 W and a time of 10 - 30 min.

[0017] When chelating, the volume ratio of the Ca3(PO4)2 suspension to the sodium dithiocarbamate solution is 1:1 - 2.

[0018] The separation refers to centrifugal separation.

[0019] The washing refers to washing with deionized water and / or ethanol. Specifically, separate the Ca3(PO4)2 precipitate obtained from the reaction and wash it with deionized water until neutral; separate the precipitate obtained from the chelation reaction and wash it successively with deionized water and ethanol.

[0020] The drying refers to drying in a vacuum at 60 °C.

[0021] Example 1

[0022] Dissolve Ca(NO3)2·4H2O and (NH4)2HPO4 separately in deionized water to prepare solutions with a concentration of 1 mol / L.

[0023] Place the Ca(NO3)2 solution in a water bath at 70 °C, and while stirring, add the (NH4)2HPO4 solution dropwise at a rate of 50 ml / min. The volume ratio of the Ca(NO3)2 solution to the (NH4)2HPO4 solution is 1.5:1.

[0024] After the dropwise addition is complete, add sodium hydroxide to adjust the pH value of the reaction system to 10, and continue to stir and react in a water bath at 70 °C for 90 min.

[0025] Centrifuge the Ca3(PO4)2 precipitate obtained from the reaction, wash it with deionized water until neutral, and then obtain a solid powder. Take 1 g of the solid powder, add 100 ml of deionized water, and disperse it evenly by ultrasonic wave twice to make a uniform suspension.

[0026] Place the suspension in a water bath at 70 °C, and while stirring, add a 0.5 mol / L sodium diethyldithiocarbamate solution. The volume ratio of the Ca3(PO4)2 suspension to the sodium diethyldithiocarbamate solution is 1:1, and carry out a chelation reaction for 100 min.

[0027] Centrifuge the precipitate obtained from the chelation reaction, wash it successively with deionized water and ethanol, and then dry it in vacuum at 60 °C to prepare the arsenic removal agent NP201 for the target alkaline leaching system.

[0028] Example 2

[0029] Dissolve Ca(NO3)2·4H2O and (NH4)2HPO4 in deionized water respectively to prepare solutions with a concentration of 1.5 mol / L.

[0030] Place the Ca(NO3)2 solution in a water bath at 65 °C, and while stirring, add the (NH4)2HPO4 solution dropwise at a rate of 50 ml / min. The volume ratio of the Ca(NO3)2 solution to the (NH4)2HPO4 solution is 2:1.

[0031] After the dropwise addition is complete, add ammonia water to adjust the pH value of the reaction system to 11, and continue to stir and react in a water bath at 75 °C for 75 min.

[0032] Centrifuge the Ca3(PO4)2 precipitate obtained from the reaction, wash it with deionized water until neutral, and then obtain a solid powder. Take 5 g of the solid powder, add 100 ml of deionized water, and disperse it evenly by ultrasonic wave twice to make a uniform suspension.

[0033] Place the suspension in a water bath at 65 °C, and while stirring, add a 0.8 mol / L sodium diethyldithiocarbamate solution. The volume ratio of the Ca3(PO4)2 suspension to the sodium diethyldithiocarbamate solution is 1:2, and carry out a chelation reaction for 120 min.

[0034] The precipitate obtained from the chelation reaction was centrifuged, washed successively with deionized water and ethanol, and then dried in vacuo at 60 °C to obtain the arsenic-removing agent NP201 for the target alkaline leaching system.

[0035] Example 3

[0036] Ca(NO3)2·4H2O and (NH4)2HPO4 were respectively dissolved in deionized water to prepare solutions with a concentration of 2 mol / L.

[0037] The Ca(NO3)2 solution was placed in a water bath at 75 °C, and the (NH4)2HPO4 solution was added dropwise at a rate of 50 ml / min with stirring. The volume ratio of the Ca(NO3)2 solution to the (NH4)2HPO4 solution was 1:1.

[0038] After the addition was completed, sodium carbonate was added to adjust the pH value of the reaction system to 10.5, and the reaction was continued with stirring in a water bath at 80 °C for 60 min.

[0039] The Ca3(PO4)2 precipitate obtained from the reaction was centrifuged, washed with deionized water until neutral, and then a solid powder was obtained. 10 g of the solid powder was taken, 100 ml of deionized water was added, and ultrasonic dispersion was carried out twice to make it uniformly dispersed to form a uniform suspension.

[0040] The suspension was placed in a water bath at 70 °C, and a 1 mol / L sodium diethyldithiocarbamate solution was added dropwise with stirring. The volume ratio of the Ca3(PO4)2 suspension to the sodium diethyldithiocarbamate solution was 1:1.5, and the chelation reaction was carried out for 90 min.

[0041] The precipitate obtained from the chelation reaction was centrifuged, washed successively with deionized water and ethanol, and then dried in vacuo at 60 °C to obtain the arsenic-removing agent NP201 for the target alkaline leaching system.

Claims

1. A method for preparing a dearsenicizing agent NP201 for an alkaline leaching system, characterized in that: The steps include: Dissolve Ca(NO3)2·4H2O and (NH4)2HPO4 in deionized water to prepare a solution with a concentration of 1~2 mol / L; Place the Ca(NO3)2 solution in a water bath at 65-75°C and add (NH4)2HPO4 solution dropwise while stirring; After the addition is complete, adjust the pH value of the reaction system to alkaline, and continue stirring the reaction in a water bath at 70-80°C for 60-90 minutes; The Ca3(PO4)2 precipitate obtained by the reaction is separated, washed to neutrality, and then deionized water is added to make a uniformly dispersed suspension; then it is placed in a water bath at 65-70°C, and 0.5-1 mol / L sodium dithiocarbamate solution is added while stirring, and the chelation reaction is carried out for 90-120 minutes; The precipitate obtained by the reaction is separated, washed and dried to obtain the target arsenic removal agent NP201 for the alkaline leaching system.

2. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: The water bath temperature was 70°C during the dropwise addition.

3. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: The dropping speed is 50 ml / min.

4. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: When adding dropwise, the volume ratio of the Ca(NO3)2 solution to the (NH4)2HPO4 solution is 1~2:

1.

5. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: The pH value of the reaction system is 10-11.

6. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: When the suspension is prepared, the mass volume ratio of the Ca3(PO4)2 precipitate to deionized water is 1-10 g / 100 ml.

7. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: During chelation, the volume ratio of the Ca3(PO4)2 suspension to the sodium dithiocarbamate solution is 1:1-2.

8. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: The separation refers to centrifugal separation.

9. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: The washing refers to washing with deionized water and / or ethanol.

10. The method for preparing the arsenic removal agent NP201 according to claim 1, characterized in that: The drying refers to vacuum drying at 60°C.