Magnetic separator equipment
PTMS magnetic separation
what is magnetic separation in chemistry ？
(1) High temperature excitation
The active excitation of clay minerals involves two technical routes: one is high temperature excitation. For example, when kaolin is calcined at 650-800 ° C, structural changes occur, and metakaolin having poor crystallinity is formed due to dehydration of the layered structure. Because the molecular arrangement of metakaolin is irregular and thermodynamically metastable, it has good pozzolanic activity.
Kaolin, which has been excited by high temperature, is generally used in the preparation of geopolymers, molecular sieves, and adsorbent materials because of its good activity.
(2) Acid-base excitation
Another route of active excitation of clay minerals is acid-base excitation. The surface of the clay mineral particles reacts under acidic and basic conditions to form a new polymer with clay mineral particles as the basic unit.
Under acidic conditions, the silanic hydroxyl groups on the surface of the clay mineral are connected with protons to form protonated silolic hydroxyl groups. The protonated silanol groups are condensed with silanol to remove water molecules, forming silicon siloxane bonds, releasing protons, catalyzing the subsequent condensation reaction, and gradually forming. Silicon oxide polymer.
Acid activation of clay minerals is a common activation method. The role of acid activation is to obtain partially dissolved clay mineral materials with higher specific surface area, porosity, surface acidity or to exhibit new properties for new applications. The degree of dissolution of the clay depends on the type of mineral and the reaction conditions such as acid-clay ratio, acid concentration, reaction time and reaction temperature. A typical application of clay acid activation is the activation of bentonite in hydrochloric acid or sulfuric acid. Acid-activated calcium-based bentonite can be used for decolorization of edible oils and fats, and decolorization and refining of petrochemical products. In addition to traditional bentonite acid activation, other clay minerals, such as expanded vermiculite, and various non-expanded minerals (kaolinite minerals, sepiolite, attapulgite, etc.) can also be activated by acid, acid activation. It is still a hot research area.
Under alkaline conditions, the silanol on the surface of the clay mineral combines with the hydroxide to form a siloxane anion. The siloxane anion attacks the silanol nucleophilic attack, removes water molecules, forms a silicon siloxane bond, and releases hydrogen and oxygen. The root catalyzes the subsequent condensation reaction and gradually forms a silicon oxide polymer.
An important use of alkali-activated clay minerals is the preparation of geopolymers from metakaolin minerals. The geopolymer is an inorganic polymer of a three-dimensional network structure formed by a silicon oxytetrahedron and an aluminoxy tetrahedron. The geopolymer repairing materials prepared by using alkali-excited metakaolin have the characteristics of fast setting, early strength, durability, corrosion resistance and environmental protection. The study of metakaolin-based polymers involves reaction mechanisms, microstructure, chemistry, thermodynamics and mechanical stability.
