CN110921805A

CN110921805A - Attapulgite clay reduction-magnetic separation coupling continuous iron removal whitening purification method

Info

Publication number: CN110921805A
Application number: CN201911279093.5A
Authority: CN
Inventors: 冯拥军; 王兴鹏; 何俊玲; 唐平贵; 陈馨; 魏邦延
Original assignee: Beijing University of Chemical Technology
Current assignee: Gansu Huihua Technology Co.,Ltd.; Beijing University of Chemical Technology
Priority date: 2019-12-13
Filing date: 2019-12-13
Publication date: 2020-03-27
Anticipated expiration: 2039-12-13
Also published as: CN110921805B

Abstract

The invention belongs to the technical field of chemical industry, and particularly relates to an attapulgite clay reduction-magnetic separation coupling continuous iron removal whitening purification method, which adopts a reduction reaction-magnetic separation coupling method and carries out particle size screening, grinding pulping and acid leaching impurity separation on natural attapulgite clay; reducing and replacing Fe in the solution by using a reducing agent under the condition of controlling the pH value²⁺、Fe³⁺And continuously removing the reduced iron simple substance in the attapulgite clay slurry through magnetic separation to achieve the aim of removing impurities. The acid water filtered after the magnetic separation can also be used as raw material water for recycling, so that the iron removal efficiency of the attapulgite clay is improved while the discharge of acid wastewater is avoided. The method can effectively remove free iron, sulfur, phosphorus and other impurity minerals, does not damage the original crystal structure, has simple process, no waste acid discharge, high process automation and continuity degree, is environment-friendly and is convenient for industrial production. Book (I)The invention can promote the effective and high-value utilization of attapulgite clay resources.

Description

Attapulgite clay reduction-magnetic separation coupling continuous iron removal whitening purification method

Technical Field

The invention relates to an attapulgite clay impurity removal technology, in particular to an attapulgite clay iron removal whitening purification method. The method is simple and convenient to operate and environment-friendly.

Background

Attapulgite clay, also known as palygorskite, is a natural hydrous magnesium aluminum silicate-rich clay mineral with a rod-like microscopic morphology. It consists of tetrahedral-octahedral-tetrahedral (T-O-T) talc-like ribbons parallel to the fiber axis, connected by reversed Si-O-Si bonds between the ribbons, forming two continuous tetrahedral sheets and one discontinuous octahedral sheet. Due to the unique pore structure and surface properties, the attapulgite clay is widely applied to a plurality of aspects such as an adsorbent, a catalyst, a polymer functional auxiliary material, a fluorescent material and the like.

The natural attapulgite clay has darker color (brick red, brown, gray yellow and gray) due to the fact that a small amount of Fe (II) is contained to replace Mg (II) or Al (III) in an octahedron structure, and the Fe (III) replaces Mg (II) or Al (III) in the octahedron structure to enable the attapulgite to have brick red. These special colors severely limit the field of application of the attapulgite. In addition, natural attapulgite is often associated with impurity minerals such as quartz, feldspar, illite, chlorite and muscovite. Therefore, how to effectively realize the whitening and purification of the attapulgite is one of the main bottlenecks of the high-efficiency and high-value utilization of the attapulgite resources at present.

Chinese patent CN 101818000 discloses a method for realizing white-turning of attapulgite clay by using oxalic acid and titanium trichloride for reduction after acidification by sulfuric acid. Firstly, smashing attapulgite, sieving the smashed attapulgite with a 100-mesh sieve, roasting and activating the attapulgite for 1 hour at the temperature of 300-700 ℃, then acidifying the attapulgite with 3-8% sulfuric acid, soaking the attapulgite, washing the attapulgite with a large amount of distilled water until the pH value is 6.0-7.0, and then drying, grinding and sieving the attapulgite to obtain the acidified attapulgite; then, acidified attapulgite is used for pulping, and reacts with oxalic acid and titanium trichloride for acidification, and white attapulgite clay is obtained after centrifugation, washing and drying. However, the method needs a multi-step process, the process is complex, a large amount of acid-containing wastewater needs to be discharged in the washing process, and the post-treatment cost of environmental treatment is high. The method is characterized in that the method comprises the following steps of taking dimethyl sulfoxide and water as mixed solvents, treating red attapulgite clay by a one-step solvothermal method according to the documents Z.F.Zhang, W.B.Wang, G.Y.Tian, Q.Wang, A.Q.Wang, appl.Clay Sci.2018,159 and 16-24, and when the volume ratio of the dimethyl sulfoxide to the water is 2:1, the whiteness of the product reaches 83.3%. The method comprises the following steps of dispersing brick red attapulgite in hydroxylamine hydrochloride solution, mechanically stirring at 80 ℃ for more than 24 hours, centrifuging, washing with water, vacuum drying at 60 ℃, crushing and sieving to obtain white attapulgite, wherein the documents are Z.F.Zhang, W.B.Wang, Y.R.kang, Q.Wang, A.Q.Wang, Powder technology.2018,327 and 246-254. The above documents all employ a batch operation method, which is disadvantageous for continuous processing. In addition, not only is the production and environmental protection cost increased by introducing the organic solvent, but also the impurity iron is not extracted, and the hidden trouble of secondary pollution still exists.

The invention utilizes the reducing agent to reduce the iron in the attapulgite into the iron simple substance under the acidic condition, and absorbs the simple substance iron by the magnet, thereby realizing the purpose of continuous iron removal, whitening and purification by attapulgite reduction reaction-magnetic separation coupling, and the washing water is circularly used as the water for preparing diluted acid and pulping, and the process is simple and environment-friendly.

Disclosure of Invention

The invention aims to provide a method for purifying attapulgite clay by removing iron and turning white, which is simple, convenient, efficient and environment-friendly.

The invention provides an iron-removing whitening purification method of attapulgite clay, which comprises the following specific steps:

A. according to the mass ratio of the attapulgite clay to be whitened to water of 1:1-9, beating the attapulgite clay to be whitened into concave-convex rod slurry by using a grinding beater, adjusting the pH value of the slurry to 0-5 by using dilute acid, and removing carbonate type impurity minerals to obtain acidic attapulgite slurry;

B. adding the acidic attapulgite slurry into an acid-resistant reactor, and continuously and slowly adding a reducing agent under mechanical stirring, wherein the adding amount of the reducing agent is 1-30% of the mass of the attapulgite clay; forming attapulgite reducing slurry from the acidic attapulgite slurry under the action of a reducing agent, and adjusting the pH value of the slurry to 0-5 by using dilute acid; starting a peristaltic pump to enable the attapulgite reducing slurry to circularly flow through a magnetic separator, immediately magnetically coupling and separating iron elementary substances generated by reduction reaction in the slurry, continuously circulating until the slurry becomes pure white, stopping circulating, discharging and filtering to obtain a white attapulgite filter cake; recovering the filtered acid water, and then using the recovered acid water for pulping in the step A for recycling; the white attapulgite filter cake is dried in a drying oven to obtain the white attapulgite powder.

The reducing agent is one of magnesium powder, aluminum powder, zinc powder, sodium borohydride, lithium aluminum hydride, hydrazine hydrate and ammonia borane, and the reducing agent is used for reducing free Fe in the solution²⁺And Fe³⁺Reducing the ions into iron simple substance for removal;

the diluted acid is one of hydrochloric acid, sulfuric acid and phosphoric acid, and the mass fraction of the diluted acid is 1-10%;

the magnetic separator is characterized in that a loop pipe is externally connected with the reactor, a peristaltic pump is additionally arranged at the front end of the loop pipe, and a magnetic field device is arranged outside the loop pipe; the working principle is that a pump is used for pumping the slurry in the reaction kettle into a magnetic separator, and the iron in the slurry is removed under the action of an external magnetic field; the loop pipe is a glass pipe or a stainless steel pipe lined with tetrafluoroethylene; the magnetic field device is an electrified magnet or a permanent magnet.

FIG. 1 is a comparative XRD analysis chart of attapulgite clay before and after iron removal in example 1. it can be seen from FIG. 1 that the attapulgite clay has been further purified after continuously removing iron and whitening, while the crystal structure of attapulgite clay has not been changed and some impurity minerals (such as chlorite, dolomite, etc.) have been removed.

The invention adopts a reduction reaction-magnetic separation coupling method, and adopts a reducing agent to reduce and displace Fe in a solution under the condition of controlling a pH value by screening the particle size of the attapulgite clay, grinding and pulping, acid leaching and impurity precipitation²⁺、Fe³⁺And further continuously removing the iron content in the attapulgite clay through magnetic separation and simultaneously recovering the iron simple substance, wherein the acid water after the magnetic separation can be used as raw material water for recycling, thereby avoiding the discharge of acid wastewater and simultaneously improving the iron removal efficiency of the attapulgite clay. The method can effectively remove free iron, sulfur, phosphorus and other impurity minerals, does not damage the original crystal structure, has simple process, no waste acid discharge, high process automation and continuity degree, is environment-friendly and is convenient for industrial production.

Description of the drawings:

FIG. 1 is a XRD (X-ray diffraction) contrast diagram before and after continuous iron removal by coupling reduction-magnetic separation of attapulgite clay in example 1.

The specific implementation mode is as follows:

example 1

(1) Taking Gansu brick red attapulgite clay as an example, crushing mineral powder, pulping by using a grinder, adding water to adjust the solid-to-liquid ratio of the pulp to be 1:4, adjusting the pH value of the pulp to be 0-1 by using 8% phosphoric acid by mass fraction, and mechanically stirring and soaking for 2 hours.

(2) Adding the acidic attapulgite slurry into an enamel reaction kettle with a glass loop magnetic separator, slowly adding aluminum powder into the slurry under mechanical stirring, adding the aluminum powder with the mass being 10% of that of the attapulgite clay, and continuously stirring to form attapulgite reducing slurry; dropwise adding 8% phosphoric acid to keep the pH value of the slurry stable within the range of 0-1 in the reaction process; starting the peristaltic pump to make the attapulgite reducing slurry continuously flow through the magnetic separator and then return to the reaction kettle, and circulating until the attapulgite slurry is completely whitened. The white attapulgite slurry is filtered and dried to obtain the attapulgite product. The whiteness of the sample was measured with a color difference meter to be 68.3%. Analyzing by X-ray fluorescence spectrum analyzer for sample elements, wherein Fe₂O₃3.78% of SO₃1.62 percent of P₂O₅The mass fraction is 0.19%.

Example 2

(1) Taking Gansu brick red attapulgite clay as an example, crushing mineral powder, pulping by using a sand mill, adding water to adjust the solid-to-liquid ratio of the pulp to be 1:2, adjusting the pH value of the pulp to be 3-5 by using 5% sulfuric acid by mass fraction, and mechanically stirring and soaking for 1 hour.

(2) Adding the acidic attapulgite slurry into an enamel reaction kettle with a magnetic separator, slowly adding sodium borohydride into the slurry under mechanical stirring, adding the sodium borohydride with the mass being 8% of that of the attapulgite clay, and continuously stirring to form attapulgite reducing slurry; starting a peristaltic pump, enabling the attapulgite reducing slurry to continuously flow through a magnetic separator and then return to the reaction kettle, and dropwise adding 5% sulfuric acid to keep the pH value of the slurry in the reaction process within the range of 3-5; continuously circulate toThe attapulgite slurry is completely whitened. The white attapulgite slurry is filtered and dried to obtain the attapulgite product. The whiteness of the sample measured in the same manner as in example 1 was 70.2%, and Fe in the sample₂O₃2.60 percent of SO₃1.30% by mass of P₂O₅The mass fraction is 0.13%.

Example 3

(1) Taking Gansu brick red attapulgite clay as an example, crushing mineral powder, pulping by using a basket grinder, adding water to adjust the solid-to-liquid ratio of the slurry to 1:9, adjusting the pH value of the slurry to 0-3 by using 10% hydrochloric acid by mass fraction, and mechanically stirring and soaking for 0.5 hour.

(2) Adding the acidic attapulgite slurry into an enamel reaction kettle with a magnetic separator, slowly adding magnesium powder into the slurry under mechanical stirring, adding the magnesium powder with the mass being 5% of that of the attapulgite clay, and continuously stirring to form attapulgite reducing slurry; starting a peristaltic pump to enable the attapulgite reducing slurry to continuously flow through a magnetic separator and then return to the reaction kettle, and dropwise adding hydrochloric acid with the mass fraction of 10% to keep the pH value of the slurry between 0 and 3 in the reaction process; continuously circulating until the attapulgite slurry is completely whitened. The white attapulgite slurry is filtered and dried to obtain the attapulgite product. The whiteness of the sample was 80% as measured in the same manner as in example 1, and Fe in the sample₂O₃1.12% by mass of SO₃0.05% by mass of P₂O₅The mass fraction is 0.09%.

Claims

1. A method for purifying attapulgite clay through reduction-magnetic separation coupling and continuous iron removal and whitening conversion comprises the following specific steps:

B. adding the acidic attapulgite slurry into an acid-resistant reactor, and continuously and slowly adding a reducing agent under mechanical stirring, wherein the adding amount of the reducing agent is 1-30% of the mass of the attapulgite clay; the method comprises the steps of forming attapulgite reducing slurry from acidic attapulgite slurry under the action of a reducing agent, and adjusting the pH value of the slurry to be 0-5 by using a dilute acid (the pH value is consistent with that of the embodiment, and the range of applicable acidity is different because of different reducing agents, wherein the range of the applicable acidity comprises the range of all reducing agents in the embodiment); starting a peristaltic pump to enable the attapulgite reducing slurry to circularly flow through a magnetic separator, immediately magnetically coupling and separating iron elementary substances generated by reduction reaction in the slurry, continuously circulating until the slurry becomes pure white, stopping circulating, discharging and filtering to obtain a white attapulgite filter cake; recovering the filtered acid water, and then using the recovered acid water for pulping in the step A for recycling; the white attapulgite filter cake is dried in a drying oven to obtain the white attapulgite powder.