532results about "Magnesia" patented technology

The invention provides a large-area coated lithium manganate positive electrode material and a preparation method thereof, and belongs to the technical field of energy materials, and the large-area coated lithium manganate positive electrode material comprises a lithium manganate positive electrode material body subjected to grain boundary pretreatment and a coating layer coating the surface of the lithium manganate positive electrode material body. The general molecular formula of the lithium manganate positive electrode material body subjected to grain boundary pretreatment is Li < 1 + a > Mn < 2-b > MbO4, M is a doping element, a is more than or equal to-0.1 and less than or equal to 0.3, and b is more than or equal to 0 and less than or equal to 0.3; the surface coating layer comprises an M'coating element. The lithium manganate positive electrode material body subjected to grain boundary pretreatment can realize large-area coating, and the lithium manganate positive electrode material subjected to special grain boundary pretreatment and large-area coating has excellent structural stability, so that corrosion of an electrolyte to lithium manganate is relieved, Mn dissolution at a high temperature is inhibited, and the lithium manganate positive electrode material has good electrochemical performance. Therefore, the lithium manganate positive electrode material has excellent high-temperature circulation and high-temperature storage performance, and the method is simple in process and can be implemented and popularized.

The invention relates to a method for sequestering CO2, which comprises the steps of providing a starting product comprising at least 20% by mass of one or more of the following components, ultramafic rocks, weathering products of ultramafic rocks, olivine and / or industrial waste materials, homogenizing the starting product and hydro-thermally treating the homogenized starting product in a heat treatment apparatus at a temperature of above 100° C. for at least 24 hours. Furthermore, the converted starting product is dewatered of bound water by means of thermal treatment and / or reaction grinding. Subsequently, the product thus obtained is contacted with CO2, wherein the latter is bound.

The invention discloses a method for comprehensively recovering silicon and magnesium based on rotary kiln-electric furnace type ferronickel slag. The method comprises the following steps: carrying out ball milling, leaching and solid-liquid separation on the rotary kiln-electric furnace type ferronickel slag, standing supersaturated silicon in a leaching solution at normal temperature to generate a gel phenomenon, stirring and crushing to obtain a mixed phase of a magnesium sulfate solution and a silica gel block, and separating the gel solution to obtain a magnesium sulfate crude solution and wet crude silica gel; preparing high-purity hydrated magnesium sulfate with the purity of 99.9% from the magnesium sulfate crude liquid through processes of purification, crystallization and the like; the wet coarse silica gel is subjected to further alkali dissolution, gel forming and other processes to produce silica gel with the purity of 99%; the method has the advantages of low energy consumption, high product added value and element recovery rate and convenience in industrialization, and has excellent popularization and application prospects.

A negative active material, a method of preparing the negative active material, and a rechargeable lithium battery including the negative active material are disclosed. The negative active material may include a crystalline carbon core and a magnesium (Mg)-included coating layer on a surface of the core, wherein the Mg-included coating layer may include MgO and MgxSiOy (1≤x≤2 and 3≤y≤4).

The invention discloses a preparation and application method of active magnesium oxide for cobalt precipitation, which comprises the following steps: adding acetate during preparation of an active magnesium oxide precursor magnesium hydroxide to obtain magnesium hydroxide with a double-tooth structure; when magnesium oxide is prepared through calcination, conversion from magnesium hydroxide to magnesium oxide can be achieved at a low temperature, and meanwhile high activity is obtained; and finally, the magnesium oxide slurry is added into the cobalt precipitation pre-solution for cobalt precipitation, the cobalt precipitation effect is good, and the obtained coarse cobalt hydroxide cobalt is high in grade. The magnesium hydroxide regulating agent is used for promoting generation of magnesium oxide rich in active sites, the magnesium hydroxide regulating agent is applied to the wet metallurgy cobalt deposition process, the cobalt deposition effect of active magnesium oxide prepared through a chemical method is effectively improved, other methods except for the method for reducing the particle size and promoting the activity of magnesium oxide are developed, acetate is selected as the magnesium hydroxide regulating agent, the dosage is small, and the cost is low. Magnesium oxide obtained through calcination is high in purity, the cobalt deposition process is not affected, unit consumption of magnesium oxide can be reduced, and cost is saved.

The invention discloses a magnesium oxide calcining process, which adopts an automatic control system in conjunction with a mechanical arm to realize digital control according to weight, time, formula, and raw material characteristics, so that industrial primary magnesium oxide can be automatically, accurately, safely, and efficiently intelligently loaded / unloaded, and the entire production realizes an automated intelligent production line, which only requires 2-3 people to operate, and can realize continuous production with high production efficiency; the track kiln calcination adopts segmented and zoned control to realize fuzzy and accurate temperature control in each calcination area, and the combustion is sufficient and the environmental protection performance is good; in addition, the hot air and the materials carried by it in the calcination stage are partly used for preheating in the preheating section, and partly used for the magnesium carbonate production system, so as to realize recycling and reduce costs; the obtained food-grade magnesium oxide meets or exceeds the requirements of national standards. The utilization of industrial primary magnesium oxide, a process raw material, is conducive to the economical development and high-efficiency comprehensive utilization of Qinghai magnesium resources, and improves the added value of products.

The invention provides low-moisture-absorption and high-thermal-conductivity electrical-grade magnesium oxide and a preparation method thereof.The preparation method comprises the steps that silicon powder and silica sol are mixed to serve as coating slurry; carrying out coating treatment on the fused magnesium oxide by using the coating slurry, and then drying and screening to prepare silicon-coated fused magnesium oxide powder; the preparation method comprises the following steps: performing multi-stage preheating treatment and nitriding treatment on silicon-coated fused magnesium oxide powder in a nitrogen atmosphere, so that silicon powder on the surface of magnesium oxide is nitrided to form molten silicon nitride, and finally cooling and sizing to obtain high-temperature electrical-grade magnesium oxide powder with a spherical core-shell structure. The electrical grade magnesium oxide powder can resist high temperature and moisture, more importantly, the heat conduction performance of magnesium oxide is ensured, and the flowability and filling efficiency of the powder are improved.

The invention provides a coated modified lithium cobalt oxide material, a preparation method thereof, a positive electrode and a lithium ion battery. The preparation method comprises the following steps: providing a mixture, wherein the mixture sequentially comprises first lithium cobalt oxide particles, a coating agent and second lithium cobalt oxide particles from bottom to top; sequentially carrying out first mixing, second mixing and third mixing on the mixture; and sintering to obtain the coated modified lithium cobalt oxide material. The D50 particle size of the first lithium cobalt oxide particles is larger than that of the second lithium cobalt oxide particles; the mixing rotating speeds of the first mixing, the second mixing and the third mixing are sequentially increased. In the lithium cobalt oxide coating modification process, the positions of the first lithium cobalt oxide particles, the second lithium cobalt oxide particles and the coating agent in the mixture in the vertical direction are designed to form a sandwich structure, and a three-stage mixing process is combined, so that the mixing uniformity of the coating agent and the lithium cobalt oxide material is remarkably improved, and the coating performance of the lithium cobalt oxide material is improved. And uniform coating of the coating element on the surface of the lithium cobalt oxide material is realized.

The invention discloses an MgO-C nano chain, a preparation method thereof and application of the MgO-C nano chain as a wave-absorbing material, a horizontal tube furnace is adopted for preparation, and an evaporation area and a reduction area are arranged at the two ends of a furnace body respectively; taking Mg (acac) 2 as a precursor, and placing the precursor in an evaporation area; placing a substrate for collecting products in a reduction area; inert gas is adopted as carrier gas and reaction atmosphere, a vacuum pump system is used for maintaining the internal pressure intensity of the system, reaction is conducted, and the MgO-C nano chain is collected on the substrate. In the MgO-C nano chain, the nano MgO particles are connected into a three-dimensional structure through carbon, the wave-absorbing effects such as interface polarization and multiple scattering reflection are enhanced by means of the unique structure, the wave-absorbing performance is greatly improved, and the frequency band is widened. The material has good microwave absorption performance, and has a very good application prospect in the fields of stealth technology and electromagnetic shielding.

The present application provides a method for extracting lithium from salt lakes. The method comprises the following steps: (1) subjecting concentrated brine to ammonia vapor magnesium precipitation treatment to obtain a magnesium-removed filtrate and filter residue; (2) mixing the filter residue with hydrobromic acid, adjusting the pH to precipitate boric acid, and performing solid-liquid separation to obtain a filtrate and boric acid; (3) evaporating and concentrating the filtrate obtained in step (2), performing aeration treatment after drying treatment, and performing water immersion separation treatment to obtain a lithium-rich solution and magnesium oxide; (4) mixing the lithium-rich solution and lithium carbonate to perform a solid-phase transformation reaction, and filtering to obtain a purified lithium salt solution and calcium carbonate. The method of the present application can separate boron, magnesium, and calcium-lithium in one step, and further calcium removal can separate calcium and lithium, which is beneficial to obtaining high-purity lithium carbonate and reducing lithium loss caused by the adsorption of lithium by magnesium hydroxide colloid.

The mixed powder is a mixed powder for an annealing separator containing MgO as a main agent, wherein an average particle size of the mixed powder is 0.10 µm or more and 8.50 µm or less, the mixed powder contains B, and a B content contained in the entire mixed powder is 0.005 mass% or more and less than 0.040 mass%, a proportion of tri-coordinated boron in the B is 5 mass% or more and less than 70 mass%, and a ratio of a circumferential length to a thickness of primary particles containing the MgO is 6.0 or more.

Magnesium oxide is provided. When magnesium oxide is dispersed in water at a ratio of 16 g of magnesium oxide per 100 g of water, the relaxation time of TD-NMR at 40°C satisfies the requirement of 1000 milliseconds or less.

The application discloses a preparation method of low-chlorine magnesium oxide. The method comprises the following steps: adding high-chlorine magnesium hydroxide slurry into an electrolytic cell, adding an anode liquid into an anode chamber, adding a cathode liquid into a cathode chamber, and adding a reinforcing agent into the high-chlorine magnesium hydroxide slurry. A direct current electric field is applied between the anode and the cathode by using a pulse power source to remove chlorine. Under the action of the electric field, the negative-charged chlorine ions move to the anode chamber by electromigration, and the chlorine moves to the cathode chamber by electrodialysis in the form of chlorides or other soluble ions, so as to reduce the concentration of the chlorine ions in the high-chlorine magnesium hydroxide slurry. After the chlorine is removed, the magnesium hydroxide is filtered and calcined to obtain the low-chlorine magnesium oxide. The method has the advantages that the high-energy-consumption processes such as ball milling and calcining in the traditional chlorine removal process of magnesium hydroxide are avoided, the harm of the chlorine ions to the equipment is reduced, the chlorine ions in the magnesium hydroxide are removed only by electromigration and electrodialysis, and the green and efficient preparation of the low-chlorine magnesium oxide is realized.

The invention discloses a comprehensive utilization method of refining slag, which comprises the following steps: dissolving the refining slag in hydrochloric acid to obtain a refining slag pickle liquor; filtering the refining slag pickle liquor to obtain first filtrate and filter residues, and washing the filter residues to obtain first solid and first washing liquor; combining the first washing liquid and the first filtrate to obtain a second mixed solution; and adding an oxidizing agent into the second mixed solution to obtain a first precipitate. According to the method, the refining slag is subjected to acid leaching with hydrochloric acid, the PH value of the solution is adjusted, silicon dioxide, aluminum hydroxide, ferric hydroxide, calcium chloride or calcium oxide and recycled hydrochloric acid are obtained, the accumulated refining slag is decomposed into various new substances in the process reaction, the method is simple, the substance purity is high, the refining slag is recycled, and large economic value can be created; and meanwhile, mining of various resources is reduced. And a new direction is found for comprehensive utilization of the refining slag.

The invention discloses a magnesium oxide thermochemical heat storage material and a preparation method thereof.The preparation method comprises the following steps that S1, magnesium salt and carbonate are weighed and added into deionized water to be dissolved, and a magnesium salt solution and a carbonate solution are formed; s2, adding the magnesium salt solution into the magnesium carbonate solution, controlling the reaction temperature to be 30-55 DEG C and the reaction time to be 3-5 hours, and filtering after the reaction; s3, drying the sample obtained in the step S2; s4, putting the dried sample into a high-temperature furnace in which the carbon dioxide or air atmosphere is controlled, and calcining to obtain the magnesium oxide thermochemical heat storage material; wherein the microstructure of the magnesium oxide thermochemical heat storage material is a coralline structure composed of nanoparticles. By accurately controlling the reaction process and the calcining atmosphere, the heat storage material with a special nanoscale structure is prepared, and the heat storage capacity of the magnesium oxide heat storage material is improved.

The invention provides an air-stable layered oxygen positive electrode material, a preparation method thereof, a positive plate and a sodium ion battery, and relates to the technical field of sodium ion batteries. The air-stable layered oxygen positive electrode material comprises an O3 type layered metal oxide and a Li3PO4-MgO amorphous passivation layer, the surface of the O3 type layered metal oxide is coated with the Li3PO4-MgO amorphous passivation layer, the chemical general formula of the O3 type layered metal oxide is Na < 1-2x > Ca < x > (Ni Cu Fe < c > Mn < d >) < 1-y > Zn < y > O < 2 >, x < = 0.075, 0 < = y < = 0.1, 0.2 < = a < = 0.3, 0 < = b < = 0.1, 0.3 < = c < = 0.4, 0.3 < = d < = 0.4, and a + b + c + d = 1. The air-stable layer oxygen positive electrode material provided by the invention has a stable crystal structure, a proper interlayer spacing, an excellent Na < + > diffusion channel and air stability.

To provide magnesium oxide with high water resistance that can be obtained through simple operation, and a method for producing the same.SOLUTION: A method for producing magnesium oxide powder comprises a first calcination step of calcining a magnesium compound to obtain a magnesium oxide sintered body, a pulverization step of pulverizing the magnesium oxide sintered body obtained in the first calcination step to obtain a magnesium oxide pulverized product, and a second calcination step of calcining the magnesium oxide pulverized product obtained in the pulverization step to obtain magnesium oxide powder. In this production method, the calcination temperature in the second calcination step is set lower than the calcination temperature in the first calcination step.SELECTED DRAWING: None

The invention relates to active magnesium oxide as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) reversely injecting a magnesium-containing solution into a carbonate solution to obtain a mixed solution; (2) reacting the mixed solution, and then performing dynamic gradient drying to obtain a basic magnesium carbonate precursor; the dynamic gradient drying comprises at least two drying stages; and (3) carrying out two-stage roasting on the basic magnesium carbonate precursor to obtain the active magnesium oxide. According to the preparation method of the active magnesium oxide provided by the invention, the reverse injection method, the solution reaction, the dynamic gradient drying and the two-stage roasting process are combined, and the crystallization kinetics and interface engineering in the preparation process are controlled, so that the prepared magnesium oxide has the characteristics of high activity, high specific surface area and high bulk density at the same time.

The invention discloses a method for modifying metal oxide through siloxane and application of the method, and belongs to the field of display. The method comprises the following steps: S1, dissolving a precursor of a metal oxide in a solvent, dropwise adding an alcoholic solution of alkali, stirring for reaction, and cleaning and drying a product to obtain metal oxide nanoparticles; s2, dissolving the metal oxide nanoparticles in water and / or alcohol to obtain a turbid liquid; and S3, adding a siloxane compound into the turbid liquid, and carrying out ultrasonic treatment, standing, filtering, cleaning and drying to obtain the siloxane-modified metal oxide nanoparticles. The modification method is simple, the performance is remarkably improved, the limitation of the traditional technology on the aspects of solution colloid stability and interface performance is broken through, and reliable technical guarantee is provided for preparation and application of novel photoelectric devices.

In some embodiments the application pertains to processes comprising reacting a component comprising an alkaline earth weak acid with a component comprising an acid to form a component comprising an alkaline earth acid anion and a component comprising a weak acid derivative. At least a portion of the component comprising the alkaline earth acid anion is reacted with a component comprising an alkali sulfate to form a component comprising alkaline earth sulfate and a component comprising an alkali acid anion. At least a portion of the component comprising alkaline earth sulfate is decomposed to form a component comprising alkaline earth oxide, or alkaline earth hydroxide, or alkaline earth carbonate, or alkaline earth sulfide, or a derivative thereof, or any combination thereof, and a component comprising sulfur dioxide, or oxygen, or sulfur trioxide, or a derivative thereof, or any combination thereof.

The invention relates to a preparation method of electrical-grade magnesium oxide for slowing down current leakage, belongs to the technical field of electrical-grade magnesium oxide, and solves the problems of poor insulativity, relatively high electrical leakage and the like in the actual use process of electrical-grade magnesium oxide. Comprising the following steps: step 1, weighing nano calcium oxide and lanthanide series metal oxide, putting the nano calcium oxide and the lanthanide series metal oxide into a quartz crucible, and uniformly mixing to obtain a primary mixed oxide auxiliary agent; 2, heating the mixed oxide auxiliary agent obtained in the step 1 in a muffle furnace, cooling to room temperature under a drying condition to obtain white powder, and grinding to obtain an oxide auxiliary agent; 3, absorbing ethyl acetate (EA), hydrogen-containing silicone oil and polycyclic aromatic hydrocarbon (D30), putting into a centrifugal tube, and uniformly mixing to obtain a liquid film coating auxiliary agent; the method has the advantages that the current leakage of the electrical-grade magnesium oxide with poor insulativity can be slowed down by adding the metal oxide aid under the condition that the original properties of the electrical-grade magnesium oxide are not changed. The method is simple, convenient and obvious in effect.

The invention discloses a calcium-magnesium separation process for dolomite tailings, which belongs to the field of dolomite tailings treatment, and comprises the following steps: crushing the dolomite tailings by a crusher until the particle size is less than 5mm, and then grinding the dolomite tailings in a ball mill until the particle size reaches 200 meshes; a magnetic separator is adopted for magnetic separation, iron impurities in the tailings are removed, then impurities such as silicon are removed through a flotation method, and the pretreated dolomite tailings are obtained; putting the pretreated dolomite tailings into a high-temperature furnace, and calcining at 950 DEG C for 2 hours; according to the method, various innovative separation technologies are combined, efficient separation of calcium and magnesium can be achieved, the purity of calcium and magnesium products is improved, the production cost is reduced, and resource waste is reduced; the industrial preparation technology of nano magnesium oxide, nano magnesium hydroxide and nano calcium carbonate developed on the basis of the separation process breaks through the bottleneck of the prior art, improves the product quality and the production efficiency, and has a good industrial prospect.

The present invention provides a method of producing hydrochloric acid, comprising reacting high-temperature gaseous chlorine and water vapour in a carbon-free reverse Deacon reaction (RDR) at a temperature of from about 450 to about 750 °Celsius to produce a mixture of gases comprising hydrogen chloride and oxygen. The chlorine is produced by fusing and electrolysing sodium or magnesium chloride in solid phase. The water vapour comes from thermally decomposing a hydroxide of at least one of calcium, magnesium and iron in the absence of oxygen to produce the water vapour without any admixture of oxygen (e.g., from atmospheric air). The mixture of gases produced by the RDR is immediately contacted with liquid water to dissolve the hydrogen chloride therein, thereby producing hydrochloric acid and a stream of tail gases. Heat is extracted from the hydrochloric acid to maintain its temperature substantially constant until the stream of tail gases is no longer in contact therewith. Thus the chlorine and water vapour are both supplied to the RDR at high purity and require little, if any, preheating. Heat extracted from contacting the mixture of gases with liquid water may be used to keep the RDR within its range of operating temperatures. Oxygen can be separated from the stream of tail gases, and the oxygen-depleted stream can be recycled back to the RDR to give a high percentage conversion of chlorine to hydrogen chloride. The RDR may be uncatalysed and kept within its operating temperature range by radio-frequency volumetric heating in at least one of the IEEE Ku-, K- and Ka-bands. The invention also provides a corresponding apparatus (1h) for producing hydrochloric acid, comprising an electrolytic cell (10) for the electrolysis, a gas-tight kiln (20) for the thermal decomposition, a gas-phase reactor (30) for the RDR, and an absorber (40) for dissolving the hydrogen chloride in the liquid water. The apparatus (1h) may further comprise a separator (80) for separating the stream of tail gases into the oxygen-depleted stream and a stream of oxygen, which may be fed to a steelmaking apparatus (90), for example. The liquid water for dissolving the hydrogen chloride can come from condensing water vapour obtained by drying an aqueous solution of sodium or magnesium chloride or of sodium hydroxide. The apparatus (1h) may therefore also comprise a dryer (60) for drying this aqueous solution, and a condenser (70) for condensing the water vapour thus obtained. Sodium chloride or magnesium chloride in solid phase derived from drying the aqueous solution may be recycled back to the electrolytic cell (10). Electricity for the electrolysis can come from a renewable resource. At least some of the heat for the thermal decomposition may come from the liquid metal which is a co-product of the electrolysis. The invention is therefore highly energy efficient and requires little, if any, extra energy, apart from the electricity required for the electrolysis. The invention also uses commonly available ingredients and produces no greenhouse gases.

The invention provides spodumene impurity residue removal lithium extraction equipment and a lithium chloride and magnesium oxide preparation process, and relates to the technical field of solid waste treatment, the spodumene impurity residue removal lithium extraction equipment comprises a water bath extraction box, a first mounting plate, a second mounting plate, a reciprocating mechanism and a stirring mechanism; a first mounting plate and a second mounting plate are respectively mounted at the top of the water bath extraction box, the reciprocating mechanism comprises a motor mounted at the top of the first mounting plate, an output shaft key slot of the motor is connected with a turntable, and a limiting frame is fixedly arranged at the bottom of the first mounting plate. According to the scheme, the reciprocating mechanism is matched with the stirring mechanism to rotate in a reciprocating manner, so that the lithium dissolution and separation rate can be increased, a local dead zone formed by single stirring can be broken through the compound motion of reciprocating rotation and stirring, a lithium-containing filtrate forms a strong turbulence and shear effect in the water bath extraction box, updating of a surface leaching agent can be accelerated, and the extraction efficiency is improved. The diffusion resistance of lithium ions on a solid-liquid interface is reduced, so that the dissolution rate of lithium from a solid state to a solution is remarkably increased, and the overall extraction period is shortened.

The present application relates to the field of magnesium-aluminum composite oxide preparation, and discloses a magnesium-aluminum composite oxide and a preparation method thereof.The method comprises the following steps: (1) under anhydrous conditions, performing a first reaction on aluminum and a first aliphatic alcohol to obtain an alkoxide aluminum-containing material; (2) under the action of a catalyst, performing a second reaction on the alkoxide aluminum-containing material obtained in step (1), magnesium and a second aliphatic alcohol under anhydrous conditions; (3) performing hydrolysis on the reaction product of step (2) to obtain a magnesium-aluminum bimetallic alkoxide, and then performing optional drying and calcination to obtain a magnesium-aluminum composite oxide; wherein the first aliphatic alcohol and the second aliphatic alcohol each independently comprise n-pentanol and optionally n-hexanol. The preparation method of the magnesium-aluminum composite oxide provided by the present application can obtain a high-purity magnesium-aluminum composite oxide without subsequent purification treatment, and has the advantages of short initiation time and short reaction time.

To provide a coating member which can keep insulative after discharge processing is performed and can suppress welding of laminated members at the time of thermal processing.SOLUTION: The method for manufacturing a coating member includes: an application step of applying a magnesium hydroxide fluid on a surface of an Fe-Co-based alloy base material; a baking step of baking the base material at temperatures of 600-900°C and forming a magnesium oxide coating on the base material. The coating member has a baked coating film of magnesium oxide with a lattice constant of 4.20-4.23 Å on the Fe-Co-based alloy base material.SELECTED DRAWING: None

The objective of the present invention is to provide a method for producing a core-shell particle without requiring the synthesis of a core particle and the adjustment of the electric charge of the surface of the core particle, and to provide a method for producing a hollow particle without requiring thermal energy in a hollowing step of the core-shell particles. The method for producing the core-shell particle according to the present invention includes a step for forming a shell by directly fluorinating the surface layer of a core particle consisting of a magnesium inorganic salt. Next, the method for producing a hollow particle of a fluoride includes a step for removing only the core particle with an acid from the core-shell particle obtained by the above-mentioned producing method.

This magnesium oxide powder contains secondary particles in which a plurality of primary particles of magnesium oxide having a crystal phase and a grain boundary phase are at least partially fused together by the grain boundary phase, and a median diameter obtained by a laser diffraction scattering method is 300 µm or less.

Provided is a magnesium oxide.　This magnesium oxide, when being made into an aqueous dispersion containing the magnesium oxide at a proportion of 16 g per 100 g of water, exhibits a relaxation time satisfying 1000 milliseconds or less in TD-NMR at 40°C.

The present invention provides a new production method with which magnesium oxide having a higher purity can be obtained.　The present disclosure pertains to a production method for magnesium oxide. A production method for magnesium oxide according to the present disclosure comprises: a carbonation step; a separation step; a crystallization step; and a firing step.　The carbonation step is for blowing carbon dioxide gas into a suspension liquid of magnesium hydroxide and calcium hydroxide to obtain an aqueous magnesium hydrogencarbonate solution.　The separation step is for subjecting the aqueous magnesium hydrogencarbonate solution to solid-liquid separation.　The crystallization step is for crystallizing magnesium carbonate from the aqueous solution obtained in the separation step.　The firing step is for firing the magnesium carbonate to obtain magnesium oxide.　In addition, the present disclosure is characterized in that the pH of the suspension liquid is adjusted in the carbonation step.