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Method for preparing active magnesium oxide from carbide slag and preparation method of magnesium cement

A technology of activated magnesia and carbide slag, applied in the direction of magnesia, etc., can solve problems such as land erosion, easy leakage and pollution of road surfaces, and large land occupation

Pending Publication Date: 2020-09-11
QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Most PVC manufacturers separate the calcium carbide slag slurry by gravity sedimentation, and then recycle the supernatant; after further dehydration, the calcium carbide slag still has a moisture content of 40%-50%, and it is in the form of paste, which is easy to leak and pollute during transportation. On the pavement, long-term accumulation not only occupies a large amount of land, but also has a serious erosion effect on the land

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  • Method for preparing active magnesium oxide from carbide slag and preparation method of magnesium cement
  • Method for preparing active magnesium oxide from carbide slag and preparation method of magnesium cement
  • Method for preparing active magnesium oxide from carbide slag and preparation method of magnesium cement

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preparation example Construction

[0048] The present invention also provides a preparation method of magnesium cement, which is based on the calcined product obtained by the above preparation method; then the calcined product, magnesium chloride and water are mixed according to a certain ratio, and the magnesium cement is obtained after curing.

[0049] Among them, the ratio of active magnesium oxide to magnesium chloride is 5-8:1, and magnesium cement is made of MgO-MgCl 2 -H 2 O forms a ternary system, when MgO and MgCl 2 When the ratio is greater than or equal to 5, the hydration product is 518 phase and Mg(OH) 2 ; When MgO and MgCl 2 When the ratio is less than 5, the hydration products are 318 phase and 518 phase. In order to maintain the stability of the 518 phase in the magnesium cement ternary system, the ternary system should contain a certain amount of Mg(OH) 2 , so MgO and MgCl 2 The proportioning ratio is preferably greater than 5.

[0050] It is worth noting that in the actual production pro...

Embodiment 1～6

[0083] The pretreated precursors were calcined at 400°C, 500°C, 600°C, 700°C, 800°C, and 900°C, respectively, and the calcination time was 30 minutes to obtain 6 kinds of calcined products.

[0084] Carry out XRD analysis respectively to above-mentioned 6 parts of calcined products, obtain spectrum see for details Figure 4 . It can be seen from the figure that the 400°C calcined product of the precursor contains incompletely decomposed Mg(OH) 2 , Mg(OH) in the calcined product at 500°C 2 Characteristic peaks have completely disappeared. It shows that when the temperature is greater than 500°C and calcined for 30 minutes, the Mg(OH) in the raw material 2 It will be completely pyrolyzed to generate MgO, and the reaction formula is:

[0085]

[0086] In addition, by Figure 4 It can be seen that with the increase of calcination temperature, the CaCO 3 The characteristic peaks also tend to decrease gradually. There is obvious CaCO in the calcined product at 500℃ 3 Char...

Embodiment 7～18

[0090] The pretreated precursor was divided into 12 parts and calcined at 400°C, 500°C, 600°C, 700°C, 800°C, and 900°C for 60 min and 90 min, respectively, to obtain 12 different calcined products.

[0091] The mass change curves of the precursors in different calcination conditions measured in Examples 1 to 18 are as follows: Figure 5a shown. It can be seen from the figure that with the increase of calcination temperature, the mass loss rate increases gradually. At 400℃~500℃, the mass loss rate increases significantly with the increase of holding time. The mass loss rate from 500℃ to 900℃ increases slowly with the increase of calcination temperature. From 500℃ to 900℃, the mass loss rate does not change significantly with the extension of the holding time. Therefore, from the perspective of energy consumption, when calcining at 400°C to 500°C, the selection range of holding time is 30min to 90min; when calcining at 500°C to 900°C, the holding time is more suitable for 30m...

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Abstract

The invention discloses a method for preparing active magnesium oxide from carbide slag and a preparation method of magnesium cement. The method for preparing the active magnesium oxide from carbide slag comprises the following steps of: S1, preparing carbide slag and magnesium chloride into slurry, and carrying out reaction to generate a precursor; and S2, calcining the precursor at 500-900DEG Cfor less than 60min to obtain a calcined product, wherein the activity of magnesium oxide in the calcined product is 80% or more. The preparation method of magnesium cement comprises the following steps of: conducting the above steps of preparing the active magnesium oxide from the carbide slag; then mixing the calcined product, magnesium chloride and water according to a certain ratio to obtain magnesium cement; wherein the mass ratio of the active magnesium oxide to the magnesium chloride is 5-8:1, and the mass ratio of the magnesium chloride to water is 1:8-19. The two processes have greatsignificance in solving the treatment problem of salt lake by-products magnesium chloride and carbide slag.

Description

technical field [0001] The invention relates to the technical field of magnesium cement preparation, in particular to a method for preparing activated magnesium oxide from carbide slag and a preparation method for magnesium cement. Background technique [0002] The Qaidam area of ​​Qinghai is rich in magnesium resources, mostly in the form of a large amount of magnesium chloride left over from the mining of potassium fertilizers in salt lakes. When producing 1 ton of potassium chloride, about 40 cubic meters of brine will be produced as a by-product, which contains about 33% magnesium chloride. The output of potassium chloride in Chaerhan Salt Lake exceeds 1.5 million tons, and the annual discharge of magnesium chloride brine exceeds 60 million cubic meters. Its annual discharge has exceeded three times the total amount of sea salt by-product brine, resulting in a great waste of resources and serious environmental damage. pollute. Although researchers have used by-product ...

Claims

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Application Information

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IPC IPC(8): C01F5/08C04B9/20C04B9/06C04B9/02
CPCC01F5/08C04B9/20C04B9/06C04B9/02
Inventor 肖学英文静常成功郑卫新董金美李颖
Owner QINGHAI INST OF SALT LAKES OF CHINESE ACAD OF SCI
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