1 magnet's iron absorption and its application China is one of the earliest countries to know about the magnetic phenomenon. In the "Pipe" written in the 4th century BC, there is a record of "there are people with Cixi, and there are copper and gold under it". This is the earliest record of magnetism. A similar record can be found in the later Lu Shi Chun Qiu: "Ci Shi Zhao Tie, or Yin Zhi". The Eastern Han Dynasty is highly tempted in the "Lv's Spring and Autumn Notes": "The stone, the mother of iron is also. With the kind of mercer stone, it can lead its son. The stone is not kind, can not lead." In the ancient books of the Eastern Han Dynasty, the magnetic writings were always used. What makes it interesting is that magnets have a loving meaning in the language of many countries. In ancient times, magnets were often used for medical treatment. In "Historical Records", there is a record of "five stones scattered" for internal treatment, and the magnet is one of the five stones. In the Jin Dynasty, the use of magnets to suck out the iron needles in the body. In the Song Dynasty, some people put the magnet in the ear, and the mouth contained iron, thus curing the deafness. Magnets can only absorb iron, but not other metals such as gold, silver , copper, etc., which were known to the ancients of China. In Huainanzi, there is "Xishi can absorb iron, and it can't be used in copper." "Ci Shi can connect with iron, but it is difficult to find the tile." 2 The directionality of magnet and its application Sinan Sinan is an instrument used in the ancient Chinese to identify the direction. It is the invention of the ancient Chinese working people's understanding of the magnetic properties of objects in the long-term practice. According to the "Ancient Mine Record", it was first recorded in the magnetic mountain area of ​​Hebei during the Warring States Period. Modern archaeologists have speculated that a natural magnet ore is used to form a scorpion-shaped thing, placed on a smooth plate, engraved with a position on the plate, and the direction of the magnet guide can be used to identify the direction, which is the ancestor of the compass used now. In China, the directionality of the magnet was discovered very early, and the pointing device was made. In "Guiguzi", there is a record of "Zhengzi takes jade, it must carry Sinan, and it is not confusing." Later in the "Han Feizi", there is a record of "the first Wang Lisi South, the end of the day". In the "On the Balance", the Eastern Han Dynasty Wang Chong recorded "Shunnan's æ“ (spoon), cast it on the ground (central smooth site), and its 柢 (the long handle of the spoon) guide. 3 other natural phenomena related to magnetism High-energy charged particles in the universe, which are deflected by the earth's magnetic field to the north and south poles, collide with gas molecules and atoms in the sky, and cause molecules and atoms to excite and emit light. Chinese researchers have discovered in the ancient books of the past dynasties that from 2000 BC to 1751 AD, there were 474 records of Aurora. In the more than 180 records of the 1st to 10th centuries, there were as many as 140 exact dates. The earliest record of aurora in the West, when pushing Aristotle, he called the aurora "the crack in the sky." The name "Aurora" began with the French philosopher Gasandi. Tangent of the earth's magnetic meridian The earth is a large magnet with its geomagnetic south pole near the geographic north pole and the geomagnetic north pole near the geographic south pole. The compass is affected by the magnetic field force in the Earth's magnetic field, so one end of the guide points to the north. Magnetic beneficiation Magnetic separation definition A beneficiation method for selecting minerals in a non-uniform magnetic field using the magnetic differences of various minerals. Magnetic separation application Separation of ferrous metals (iron, manganese , chromium, etc.) ore; Colored and rare metals (such as tungsten, tantalum, etc.); Separation and decontamination of non-metallic (such as asbestos , diamond , kaolin, etc.) ore; Removal of magnetic components from solid materials and waste; Production of domestic sewage, etc.; A brief history of magnetic separation development In the three hundred years before 1 BC, China first discovered magnets, first using magnetic phenomena; in the eleventh century, it made compasses; In the 217th century, an attempt was made to select a magnetite for permanent magnets; In 31792, the United Kingdom published its first patent (magnet selection magnetite); In 41849, the United States published the first industrial magnetic separator patent; In 51855, Nottingham proposed in Sardinia the use of electromagnets to generate magnetic fields; In the 1969s, V. Trelles proposed that a pointed magnet produces a strong magnetic field on a closed magnetic system of the plane; In the year of 71960, the Jones magnetic separator was introduced in the UK; In the last ten years, some new processes, new magnetic separators, high gradient magnetic separation, magnetic fluid beneficiation, and superconducting magnetic separators have emerged.  Basic principle of magnetic separation  After the slurry is fed into the tank by the ore tank, the ore particles enter the tank feeding area in a loose state under the action of the water flow to the mine sprinkler pipe. In the action of the magnetic field, the magnetic ore particles are magnetically aggregated to form a "magnet" or "magnetic flux". The "magnet" or "magnetic flux" is magnetically applied to the magnetic pole, moves toward the magnetic pole, and is adsorbed on the cylinder. . Since the polarities of the magnetic poles are alternately arranged in the direction of rotation of the cylinder, and are fixed during operation, the "magnet" or "magnetic flux" is magnetically agitated due to the alternating magnetic poles when being rotated with the cylinder, and is mixed. The non-magnetic minerals such as gangue in the "magnet" or "magnetic flux" fall off during the flipping, and the "magnet" or "magnetic lotus" that is finally attracted to the surface of the cylinder is the concentrate. The concentrate passes to the weakest point of the magnetic system at the edge of the magnetic system, and is discharged into the concentrate tank under the action of the flushing water jet discharged from the unloading water pipe. If it is a full magnetic magnetic roller, the unloading is performed by a brush roller. Non-magnetic or weakly magnetic minerals are left in the slurry with the slurry exiting the trough, which is the tailings.  Schematic diagram of mineral magnetic separation process  Necessary and necessary conditions for achieving magnetic separation  1. There must be an inhomogeneous magnetic field with a magnetic field strength and a magnetic field gradient that is sufficiently large; 2. There must be a certain magnetic difference between minerals, that is, the specific magnetic susceptibility of the two minerals is different. 3. For minerals with strong magnetic properties, the magnetic force they receive is greater than the sum of various mechanical forces. That is, the necessary condition for the separation of magnetic ore particles is that the magnetic force of the magnetic ore particles must be greater than the mechanical force opposite to its direction. The combined force.  Why is magnetic separation only possible in non-uniform magnetic fields? The ore particles are only subjected to torque in a uniform magnetic field, such that its long axis direction is parallel to the direction of the magnetic field. In a non-uniform magnetic field, the ore particles are not only affected by the torque but also by the magnetic force. As a result, the ore particles move both in the direction of increasing magnetic field gradient and are finally attracted to the surface of the magnetic pole. In this way, the magnetic particles with different magnetic properties can be separated, so the magnetic separation can only be achieved in a non-uniform magnetic field. Mineral magnetic classification and its magnetic characteristics  A. Classification Strong magnetic minerals : It is easy to select minerals in a magnetic separator with weak magnetic field with magnetic field strength H=900~1800Oe. Few of these minerals, mainly magnetite, pyrrhotite, magnetite, titanium, zinc, iron and other spar. Weak magnetic minerals : In the magnetic field strength H = 6000 ~ 2000 Oersted, magnetic selection, some difficult to choose, and some easy to choose. Most of these types are mainly iron-manganese minerals, red, mirror, brown, and siderite; water, soft, hard, rhombohedral, etc., some containing titanium, chromium, tungsten minerals; biotite , hornblende, epidote, Chlorite, olivine, garnet, pyroxene, etc.; magnetization roasting can change mineral magnetic properties. Inclusion of a small amount of ferromagnetic minerals can significantly change the mineral magnetic properties, while the shape and particle size of the mineral itself does not affect its magnetic properties. Non-magnetic minerals : Currently, magnetic separation cannot be selected. There are many such minerals, mainly including: Part metal ores - chalcocite, galena, sphalerite, molybdenite, scheelite, cassiterite, gold and the like; Most non-metallic minerals - sulfur, coal , graphite , diamond, gypsum , kaolin, etc.; Most of the rock-forming minerals - quartz , feldspar , calcite and so on. B. Magnetic characteristics 1 magnetic characteristics of strong magnetic minerals (five points) (1) The specific magnetic susceptibility is very large (a hundred times or even thousands of times larger than weak magnetic minerals); (2) There is magnetic saturation, which can be saturated under the action of a lower magnetizing magnetic field; (3) It has a hysteresis phenomenon, and in the alternating magnetic field, it has a hysteresis loop when it is repeatedly magnetized; (4) has a magnetic transition temperature - Curie point. The Curie point of magnetite is 585 degrees; (5) The specific susceptibility is not a constant, but varies with the magnitude of the strength of the magnetizing magnetic field, its shape, particle size, degree of oxidation, and the like. 2 magnetic properties of weak magnetic minerals (four points) (1) The specific magnetization coefficient is small; (2) There is no magnetic saturation phenomenon and hysteresis; (3) The specific magnetic susceptibility is a constant, independent of the strength of the magnetizing magnetic field, its shape, particle size, etc., only related to the mineral composition; (4) When a strong magnetic mineral impurity is contained therein, even a small amount may have a large or even large influence. Basic principle of magnetization roasting of weak magnetic iron ore 1. The purpose of magnetization roasting 1 turning a weak magnetic iron mineral into a ferromagnetic iron mineral; 2 Excluding gas and crystal water in the ore; 3 makes the ore structure comfortable, which is beneficial to reduce the grinding cost; 4 Improve mineral processing technology and economic indicators. Second, the basic principle of magnetization roasting (1) Magnetization roasting is divided into three categories: reduction, neutralization and oxidative roasting. (2) Commonly used reducing agents are C, CO and H2.  How to change the surface magnetic properties of particles 1 Alkali dip magnetization The NaOH aqueous solution leaches the siderite FeCO3 to form Fe(OH)2 on the surface of the ore; the leaching compound is reoxidized to γ-Fe2O3 and Fe3O4. 2 Hydrophobic magnetization Alkali leaching dissociates the mineral surface, and the fatty acid soap forms a hydrophobic fatty acid iron film with the iron component in the iron or pulp remaining on the mineral surface, covering the surface of the mineral, and increasing the magnetic susceptibility. 3 magnetic species magnetization Adjust the slurry under certain conditions, add magnetic species (such as finely ground magnetite powder) and surfactant to selectively adhere the magnetic species to the target mineral to increase the magnetic properties of the target mineral, and then use a weak magnetic field. The equipment is separated and recycled. 4 magnetization magnetization The additional magnetic species is magnetically enhanced by selective adsorption of the minerals by the magnetizer molecules. Magnetic separation equipment  The magnetic separation process is carried out in the magnetic field provided by the magnetic separation equipment. The development of magnetic separation is the development of the magnetic separator. Since the 1980s, with the neodymium -iron- boron high magnetic rare earth With the advent of permanent magnet materials, the family of magnetic separators is growing. Classification of magnetic separation equipment Classified according to the strength of the magnetic field: weak, medium, strong. Classified according to sorting media: dry, wet. Classified according to the type of magnetic field: constant, rotating, alternating, pulsating. Classified according to sorting institutions: cylindrical, belt, disc, ring, etc.  Magnetic separation practice In order to improve the efficiency of sorting, we should follow the principle of breaking more and less grinding, losing early (stage grinding, stage selection, step by step), and accepting early harvest. Ways to improve the efficiency of fine-grained magnetite sorting Separation efficiency of micro-fine magnetite and 1) material properties - mineral magnetic properties, particle size, continuous body content, particle shape; 2) magnetic separation equipment structure, magnetic field characteristics; 3) magnetic medium motion characteristics. A selective magnetic agglomeration is the key to improve sorting efficiency Second, improve the efficiency of the magnetic separator and reduce impurities in the magnetic agglomeration. Change the magnetic structure, appropriately reduce the field strength of the selected area, add water to the sorting area, install vibrators, etc. Third, improve the process. Such as demagnetization before selection, reducing magnetic agglomeration, reducing the magnetic field strength of the back section during multi-section magnetic separation Development and utilization of four comprehensive force field magnetic separation equipment Sorting process Continuous grinding, weak magnetic-strong magnetic-anion reverse flotation process Continuous grinding, coarse subdivision, medium ore re-grinding, re-election - magnetic separation - anion reverse flotation Stage grinding, coarse subdivision selection, strong magnetic-re-election-anion reverse flotation Stage grinding, weak magnetic-fine screening-weakening magnetic-anion reverse flotation Magnetic Separation Concentrate - Cationic Reverse Flotation - Foam Concentrated Magnetic Separation - Re-grinding - Multiple Sweeping For weak magnetic iron ore, roasting-magnetic separation or the like can be used. Typical process of magnetite magnetic separation : One or two sections of dry-selected magnetic separation, finely divided products; followed by two or three stages of fine grinding, wet magnetic separation. Wet magnetic is selected by permanent magnet cylinder sorting machine. One-stage or two-stage adopts the forward flow type; the third stage or the fourth stage adopts the semi-reverse flow type; when the ball mill discharges the direct magnetic separation, the countercurrent type or the downstream type is often used. Typical process of magnetite ore dressing Pe Foam Tape,Heavy Duty Pe Foam Tape,High-Viscosity Pe Foam Tape,High Bonding Pe Foam Tape Shanghai Huike New Material Technology Co., Ltd. , https://www.shhuike.com
Introduction to magnetic dressing
　　 Ancient Chinese understanding of magnetism