CN112593090B

CN112593090B - Method for preparing nano lead sulfate by pyrogenic process regeneration of waste lead plaster

Info

Publication number: CN112593090B
Application number: CN202011343879.1A
Authority: CN
Inventors: 吕薇; 范晓慧; 苏子键; 王琰; 孙增青; 侯炜; 甘敏; 季志云; 陈许玲; 黄晓贤; 李秋雨; 曹运灿; 王杰; 黄鼎堯; 刘子健
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-11-25
Filing date: 2020-11-25
Publication date: 2022-02-11
Anticipated expiration: 2040-11-25
Also published as: CN112593090A

Abstract

The invention discloses a method for preparing nano lead sulfate by pyrogenic process regeneration of waste lead plaster, which comprises the steps of uniformly mixing the waste lead plaster with a stabilizer consisting of coke powder, calcium oxide and inert alumina, roasting at 950-1100 ℃ in an inert atmosphere, and sequentially allowing roasted volatile matters to enter a sulfur dioxide-containing weak oxidizing atmosphere for vulcanization roasting at 600-950 ℃ and a sulfur dioxide-containing strong oxidizing atmosphere for vulcanization roasting at 400-600 ℃ to obtain nano lead sulfate powder; the method uses waste lead plaster as a raw material to efficiently recover lead and obtain the high-purity nanoscale lead sulfate powder material which can be directly used as a battery-grade raw material, not only realizes waste utilization, but also obtains higher economic value, and the method is simple to operate, low in production cost, environment-friendly and capable of meeting the requirements of industrial production.

Description

Method for preparing nano lead sulfate by pyrogenic process regeneration of waste lead plaster

Technical Field

The invention relates to a method for recovering lead sulfate from waste lead plaster, in particular to a method for efficiently recovering lead from waste lead plaster to obtain high-purity nano lead sulfate, belonging to the technical field of electronic waste recovery.

Background

The development of human civilization is accompanied by the long-term exploitation and use of fossil energy, causing energy crisis and severe environmental pollution, and in recent years, new energy technology has rapidly developed. Meanwhile, batteries are an essential part of people's production and life, and are applied to a plurality of fields such as mobile electronic devices, automobiles, household appliances and the like. The lead storage battery is mature in technology and low in cost, and is the most widely used type.

With the scrapping of a large number of waste automobiles and electric vehicles, the disposal and regeneration of the disassembled waste lead storage batteries become a focus of attention, and since metallic lead is a typical heavy metal element, the metallic lead is seriously harmful to human bodies, and if the disposal is improper, the serious irreparable environmental pollution problem can be caused.

The secondary lead industry in China starts late, the proportion of the secondary lead is less than 30%, and the proportion of the secondary lead in developed countries such as Europe and America is over 80%. The main treatment process of the existing secondary lead is still a smelting process, and the lead plaster is used as a lead-containing raw material to be subjected to the processes of reducing smelting by a pyrogenic process, electrolytic refining and the like again, so that a metallic lead product is finally obtained. The wet process mainly comprises an alkali dissolution regeneration process, wherein lead is converted into plumbate under the condition of an alkaline medium, and then is converted into basic lead sulfate through regulation and control of pH and the like, so that the basic lead sulfate is regenerated into a lead plaster raw material product. Because the lead plaster has high lead content and low impurity content, the lead plaster is directly used as a smelting raw material and returns to the lead smelting process, and the comprehensive value is low; and the pyrometallurgical process has high metal loss rate and serious secondary pollution, and is not favorable for high-value utilization of the waste lead plaster.

Disclosure of Invention

Aiming at the defects of low comprehensive recovery rate of lead in waste lead plaster, low economic added value of recovered products and the like in the prior art, the invention aims to provide the method for preparing high-purity nano lead sulfate by pyrogenic process regeneration of the waste lead plaster, and the method has the advantages of simple operation, high lead recovery rate, low production cost, environmental friendliness and capability of meeting the requirements of industrial production.

In order to achieve the technical purpose, the invention provides a method for preparing nano lead sulfate by pyrogenic process regeneration of waste lead paste, which comprises the steps of uniformly mixing the waste lead paste with a stabilizer, placing the mixture in an inert atmosphere, roasting at 950-1100 ℃, sequentially allowing roasted volatile matters to enter a sulfur dioxide-containing weak oxidizing atmosphere to perform vulcanization roasting at 600-950 ℃ and a sulfur dioxide-containing strong oxidizing atmosphere to perform vulcanization roasting at 400-600 ℃ to obtain nano lead sulfate powder; the stabilizer is a mixture of coke powder, calcium oxide and inert alumina.

The key point of the method for preparing the nano lead sulfate by the pyrogenic process regeneration of the waste lead plaster is that the lead compound in the waste lead plaster is efficiently decomposed, volatilized and vulcanized by synergistically controlling the roasting atmosphere and temperature, and finally the high-purity nano lead sulfate powder is obtained. The roasting process of the waste lead paste is divided into three roasting processes with different atmospheres and different temperatures. The waste lead plaster enters a first-stage roasting area, the roasting is carried out under the control of higher temperature and weak reducing atmosphere provided by coke powder, the lead sulfate can be prevented from being directly reduced to form complex compounds such as lead sulfide and the like, the decomposition temperature of the lead sulfate is reduced under the synergistic catalysis of inert substances and the like, and the formation of metal lead and lead monoxide is promoted, so that the high-efficiency volatilization of the lead in the lead plaster is realized. The method comprises the following steps that volatilized lead oxide, lead, sulfur dioxide and other intermediate products enter a two-stage roasting area along with airflow, lead oxide, sulfur dioxide and other intermediate products can be quickly oxidized into nano lead sulfate crystal nuclei through proper adjustment to a slightly low temperature and under the common oxidation action of sulfur dioxide and oxygen, the nano lead sulfate crystal nuclei enter a three-stage roasting area, the temperature and the proportion of sulfur dioxide and oxygen are further reduced through three-stage roasting, the lead vulcanization efficiency can be further improved under the condition, meanwhile, the nano lead sulfate crystal nuclei are controlled to grow into uniform nano particles and are separated out from a gas phase, and therefore high-purity nano lead sulfate crystal powder products can be collected and obtained in the three-stage roasting area. According to the invention, the high-efficiency transformation of the lead-containing phase can be ensured by cooperatively regulating and controlling the temperature and the atmosphere in the three-stage calcination process, so that homogeneous and dispersed nano lead sulfate particles are formed.

The stabilizer provided by the invention consists of coke powder, calcium oxide and inert alumina, wherein the coke powder is a main reaction substance, lead compounds and the like are reduced and decomposed by utilizing a high-temperature solid-phase reaction, carbon monoxide and the like generated by the reaction provide a weak reducing atmosphere, so that side reaction is prevented from occurring, and the formation of metallic lead and lead monoxide is promoted; the calcium oxide and the inert alumina have the functions of improving the structural stability of the material, promoting the decomposition reaction and reducing the decomposition temperature, and do not participate in the high-temperature solid-phase reaction.

The inert alumina of the invention particularly refers to corundum crystal form alumina, which has compact structure and low reaction activity after being roasted at high temperature and is not easy to react with other metals and oxides.

Preferably, the mass of the stabilizer accounts for 3.0-5.0% of the mass of the waste lead plaster.

As a preferable scheme, the stabilizer consists of coke powder, inert alumina and calcium oxide according to the mass ratio of 1 (20-25) to (25-35). Lead in the lead plaster is mainly a mixture of lead sulfate and lead oxide, and also contains a small amount of impurity elements, and the decomposition temperature of the lead sulfate is over 1000 ℃ generally under the air atmosphere, so that the lead sulfate is difficult to decompose under the conventional conditions; according to the technical scheme, a small amount of coke powder and inert substances are added to catalyze the decomposition reaction of lead sulfate, and when the lead sulfate is decomposed into lead simple substances and lead oxide, the lead sulfate can be volatilized in a gas phase mode at the temperature lower than 1000 ℃, so that the separation and recovery of the lead element in the lead plaster are realized.

As a preferable scheme, in the roasting process under the inert atmosphere, the inert atmosphere is controlled to be 100% nitrogen, the gas flow rate is 0.1-0.3 m/s, and the roasting time is 120-240 min.

As a preferable scheme, in the process of carrying out vulcanization roasting in a sulfur dioxide-containing weak oxidizing atmosphere, the atmosphere is controlled to be a mixed gas of oxygen, sulfur dioxide and nitrogen, wherein the volume ratio of oxygen to sulfur dioxide is 15-25% and 5-10%, the rest gas is nitrogen, and the gas flow rate is 0.2-0.3 m/s. Under the preferred conditions, metallic lead, lead monoxide and the like can be rapidly converted into lead sulfate nanocrystal cores.

As a preferable scheme, in the process of carrying out vulcanization roasting in a strong oxidizing atmosphere containing sulfur dioxide, the atmosphere is controlled to be a mixed gas of oxygen, sulfur dioxide and nitrogen, wherein the volume ratio of oxygen to sulfur dioxide is respectively 25-50% and 10-20%, the rest gas is nitrogen, and the gas flow rate is 0.2-0.5 m/s. Under the optimized conditions, deep vulcanization of lead and lead oxide is facilitated, and growth of lead sulfate nanocrystal cores is facilitated to form nanoparticles with better crystallinity.

The waste lead plaster is obtained by disassembling waste lead storage batteries to obtain the lead plaster, and then drying and crushing the lead plaster.

The waste lead plaster mainly comprises lead sulfate, lead oxide and the like, and also comprises elements such as iron, copper, tin, antimony and the like, wherein impurity elements mostly exist in the form of oxides, the vapor pressure is far lower than that of lead oxide and simple substance lead, and the selective separation of lead-containing substances can be realized by utilizing the difference of the volatile properties of the substances. And the phase transformation of the lead oxide and the control of the grain growth are carried out through the atmosphere composition, and finally lead is transformed into nano lead sulfate particles and recovered, so that the material separation and the material synthesis are synchronously completed.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1) the method takes the waste lead plaster as the raw material, and prepares the high-added-value high-purity nanoscale lead sulfate product by efficiently regenerating and recycling lead, thereby not only realizing the utilization of wastes, but also obtaining higher economic value.

2) The method finally separates and synchronously prepares the nano-scale lead sulfate from the lead plaster waste by regulating and controlling the phase state conversion of the lead-containing substance, has simple preparation process, short flow, low cost and easy realization of industrial production.

Drawings

FIG. 1 XRD analysis and micro-topography analysis of the product prepared in example 1

Detailed Description

The following examples are intended to further illustrate the present disclosure, but not to limit the scope of the claims.

Comparative example 1

Taking lead plaster obtained by disassembling, drying and crushing a certain brand of lead storage battery for automobiles as a raw material (lead content is 72.3%), and placing the material in a three-section type controlled atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting region, wherein the first-stage atmosphere is 100% inert atmosphere, the roasting temperature is 1100 ℃, the air flow velocity is 0.1m/s, and the roasting time is 120 min; the volatilized intermediate product enters a second-stage roasting zone and a third-stage roasting zone along with airflow, the ratio of oxygen to sulfur dioxide in the second-stage atmosphere is 15 vol.% and 10 vol.%, the rest gas is nitrogen, the roasting temperature is 950 ℃, and the gas flow rate is 0.2 m/s; the oxygen and the sulfur dioxide account for 25 vol.% and 10 vol.% respectively in the three-stage roasting atmosphere, the rest gas is nitrogen, the roasting temperature is 400 ℃, and the gas flow rate is 0.3 m/s. The lead recovery rate is 50.2 percent, and the theoretical purity of the lead sulfate product is 80.5 percent. This comparative example is intended to illustrate that the decomposition efficiency of lead sulfate is lowered without a stabilizer, and the product contains a part of incompletely reacted substances.

Comparative example 2

Taking lead plaster obtained by disassembling, drying and crushing a certain brand of lead storage battery for automobiles as a raw material (lead content is 72.3%), firstly adding 3% of a stabilizer (composed of coke powder, inert alumina and calcium oxide in a mass ratio of 1:20:35) into the lead plaster, and blending and uniformly mixing the mixture; placing the uniformly mixed material in a two-section type controlled atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting region, wherein the first-stage atmosphere is 100% inert atmosphere, the roasting temperature is 1100 ℃, the air flow velocity is 0.1m/s, and the roasting time is 120 min; the volatilized intermediate product enters a secondary roasting zone along with airflow, the ratio of oxygen to sulfur dioxide in secondary atmosphere is respectively 25 vol.% and 10 vol.%, the rest gas is nitrogen, the roasting temperature is 950 ℃, and the gas flow rate is 0.2 m/s. The lead recovery rate is 90.2 percent, and the theoretical purity of the lead sulfate product is 34.2 percent. This comparative example is intended to illustrate that, after the addition of a stabilizer, lead is efficiently decomposed under the synergistic effect of the stabilizer, temperature and atmosphere, but only two-stage control results in incomplete reaction of a large amount of gas-phase intermediate phase, reducing the purity of the product.

Example 1:

taking lead plaster obtained by disassembling, drying and crushing a certain brand of lead storage battery for automobiles as a raw material (lead content is 72.3%), firstly adding 3% of a stabilizer (composed of coke powder, inert alumina and calcium oxide in a mass ratio of 1:20:35) into the lead plaster, and blending and uniformly mixing the mixture; placing the uniformly mixed material in a three-section type controllable atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting region, wherein the first-stage atmosphere is 100% inert atmosphere, the roasting temperature is 1100 ℃, the air flow velocity is 0.1m/s, and the roasting time is 120 min; the volatilized intermediate product enters a second-stage roasting zone and a third-stage roasting zone along with airflow, the ratio of oxygen to sulfur dioxide in the second-stage atmosphere is 15 vol.% and 10 vol.%, the rest gas is nitrogen, the roasting temperature is 950 ℃, and the gas flow rate is 0.2 m/s; the oxygen and the sulfur dioxide account for 25 vol.% and 10 vol.% respectively in the three-stage roasting atmosphere, the rest gas is nitrogen, the roasting temperature is 400 ℃, and the gas flow rate is 0.3 m/s. The lead recovery rate is 90.2 percent, the theoretical purity of the product lead sulfate is 97.5 percent, and the median particle size D50 of the lead sulfate is 152 nm. (the preparative XRD phase analysis and microstructure analysis are shown in FIG. 1)

Example 2:

taking lead plaster obtained by disassembling, drying and crushing a certain brand of lead storage battery for automobiles as a raw material (lead content is 72.3%), firstly adding 5% of a stabilizer (composed of coke powder, inert alumina and calcium oxide in a mass ratio of 1:25:25) into the lead plaster, and blending and uniformly mixing the mixture; placing the uniformly mixed material in a three-section type controllable atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting region, wherein the first-stage atmosphere is 100% inert atmosphere, the roasting temperature is 950 ℃, the air flow rate is 0.3m/s, and the roasting time is 240 min; the volatilized intermediate product enters a second-stage roasting zone and a third-stage roasting zone along with airflow, the ratio of oxygen to sulfur dioxide in the second-stage atmosphere is respectively 25 vol.% and 5 vol.%, the rest gas is nitrogen, the roasting temperature is 900 ℃, and the gas flow rate is 0.3 m/s; the oxygen and the sulfur dioxide account for 50 vol.% and 20 vol.% in the three-stage roasting atmosphere, the rest gas is nitrogen, the roasting temperature is 600 ℃, and the gas flow rate is 0.5 m/s. The lead recovery rate is 88.5 percent, the theoretical purity of the product lead sulfate is 96.2 percent, and the median particle size D50 of the lead sulfate is 126 nm.

Example 3:

taking lead plaster obtained by disassembling, drying and crushing a certain brand of lead storage battery for automobiles as a raw material (lead content is 81.6%), firstly adding 4% of a stabilizer (composed of coke powder, inert alumina and calcium oxide in a mass ratio of 1:25:35) into the lead plaster, and blending and uniformly mixing the mixture; placing the uniformly mixed material in a three-section type controllable atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting region, wherein the first-stage atmosphere is 100% inert atmosphere, the roasting temperature is 1000 ℃, the air flow velocity is 0.1m/s, and the roasting time is 180 min; the volatilized intermediate product enters a second-stage roasting zone and a third-stage roasting zone along with airflow, the ratio of oxygen to sulfur dioxide in the second-stage atmosphere is respectively 20 vol.% and 8 vol.%, the rest gas is nitrogen, the roasting temperature is 600 ℃, and the gas flow rate is 0.2 m/s; the oxygen and the sulfur dioxide account for 40 vol.% and 20 vol.% in the three-stage roasting atmosphere, the rest gas is nitrogen, the roasting temperature is 500 ℃, and the gas flow rate is 0.3 m/s. The lead recovery rate is 89.8 percent, the theoretical purity of the product lead sulfate is 96.2 percent, and the median particle size D50 of the lead sulfate is 180 nm.

Example 4:

taking lead plaster obtained by disassembling, drying and crushing a certain brand of lead storage battery for automobiles as a raw material (lead content is 81.6%), firstly adding 5% of a stabilizer (composed of coke powder, inert alumina and calcium oxide in a mass ratio of 1:20:35) into the lead plaster, and blending and uniformly mixing the mixture; placing the uniformly mixed material in a three-section type controllable atmosphere roasting furnace for controlled atmosphere roasting; placing the material in a first-stage roasting region, wherein the first-stage atmosphere is 100% inert atmosphere, the roasting temperature is 1050 ℃, the air flow velocity is 0.2m/s, and the roasting time is 200 min; the volatilized intermediate product enters a second-stage roasting zone and a third-stage roasting zone along with airflow, the ratio of oxygen to sulfur dioxide in the second-stage atmosphere is 15 vol.% and 8 vol.%, the rest gas is nitrogen, the roasting temperature is 700 ℃, and the gas flow rate is 0.3 m/s; the oxygen and the sulfur dioxide account for 40 vol.% and 20 vol.% respectively in the three-stage roasting atmosphere, the rest gas is nitrogen, the roasting temperature is 400 ℃, and the gas flow rate is 0.5 m/s. The lead recovery rate is 89.0 percent, the theoretical purity of the product lead sulfate is 97.2 percent, and the median particle size D50 of the lead sulfate is 175 nm.

Claims

1. A method for preparing nano lead sulfate by pyrogenic process regeneration of waste lead plaster is characterized by comprising the following steps: uniformly mixing waste lead paste and a stabilizer, placing the mixture in an inert atmosphere, roasting at 950-1100 ℃, sequentially introducing roasting volatile matters into a sulfur dioxide-containing weak oxidizing atmosphere to perform vulcanization roasting at 600-950 ℃ and a sulfur dioxide-containing strong oxidizing atmosphere to perform vulcanization roasting at 400-600 ℃ to obtain nano lead sulfate powder; the stabilizer is a mixture of coke powder, calcium oxide and inert alumina; the mass of the stabilizer accounts for 3.0-5.0% of the mass of the waste lead plaster; the stabilizer consists of coke powder, inert alumina and calcium oxide according to the mass ratio of 1 (20-25) to (25-35); in the process of carrying out vulcanization roasting in a sulfur dioxide-containing weak oxidizing atmosphere, controlling the atmosphere to be a mixed gas of oxygen, sulfur dioxide and nitrogen, wherein the volume ratio of oxygen to sulfur dioxide is 15-25% and 5-10%, the rest gas is nitrogen, and the gas flow rate is 0.2-0.3 m/s; in the process of carrying out vulcanization roasting in a strong oxidizing atmosphere containing sulfur dioxide, the atmosphere is controlled to be a mixed gas of oxygen, sulfur dioxide and nitrogen, wherein the volume ratio of oxygen to sulfur dioxide is 25-50% and 10-20%, the rest gas is nitrogen, and the gas flow rate is 0.2-0.5 m/s.

2. The method for preparing nano lead sulfate by pyrogenic process regeneration of waste lead plaster according to claim 1, wherein the method comprises the following steps: in the roasting process under the inert atmosphere, the inert atmosphere is controlled to be 100% nitrogen, the gas flow rate is 0.1-0.3 m/s, and the roasting time is 120-240 min.