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CN-121994738-A - Evaluation method for activity of red mud volcanic ash by Bayer process

CN121994738ACN 121994738 ACN121994738 ACN 121994738ACN-121994738-A

Abstract

The invention relates to the technical field of cement and concrete, in particular to an evaluation method of the volcanic ash activity of Bayer process red mud, which comprises the following steps of calcining the Bayer process red mud to be tested to obtain calcined Bayer process red mud, measuring the polymerization degree of the calcined Bayer process red mud by adopting a Fourier transform infrared spectrometry, wherein the polymerization degree and the activity of the Bayer process red mud are inversely related, evaluating the volcanic ash activity of the Bayer process red mud by measuring the polymerization degree, and measuring the polymerization degree of the Bayer process red mud by adopting the Fourier transform infrared spectrometry, so that the polymerization degree of the red mud is reduced along with the increase of the volcanic ash activity, and the compression strength and the dissolution solubility of Si+Al are positively related to the volcanic ash activity of the red mud.

Inventors

  • XIE MINGXING
  • CUI WENWEN
  • GUO JUNYUAN
  • DONG XIAOQIANG
  • HOU YANBIN

Assignees

  • 太原理工大学

Dates

Publication Date
20260508
Application Date
20231102

Claims (9)

  1. 1. The evaluation method of the volcanic ash activity of the Bayer process red mud is characterized by comprising the following steps of: Calcining the Bayer process red mud to be detected to obtain calcined Bayer process red mud; The polymerization degree of the calcined Bayer process red mud is measured by adopting a Fourier transform infrared spectrometry, the polymerization degree of the Bayer process red mud is inversely related to the activity, and the pozzolanic activity of the Bayer process red mud is evaluated by measuring the polymerization degree.
  2. 2. The method for evaluating the pozzolan activity of bayer process red mud according to claim 1, wherein the degree of polymerization is a degree of polymerization of [ Si (Al) O 4 ] tetrahedra in bayer process red mud.
  3. 3. The method for evaluating the pozzolan activity of bayer process red mud according to claim 2, wherein the method for calculating the degree of polymerization of [ Si (Al) O 4 ] tetrahedra is as follows: Where n=1, 2,3,4, represents the number of coordination bridge oxygen around Si, Q n is the relative area of the corresponding formants, RBO is the degree of polymerization.
  4. 4. A bayer process red mud pozzolan activity assessment method according to claim 3, wherein the relative areas of the corresponding formants are obtained by separating and fitting peak areas of samples in the range of 800-1200 cm -1 in the FTIR spectrum by Origin software.
  5. 5. The method for evaluating the pozzolan activity of bayer process red mud according to claim 4, wherein the molecular bonds of bayer process red mud in the FTIR spectrum of 800-1200 cm -1 are tested by a Fourier transform infrared spectrometer, and the measured wave number range is 400-4000 cm -1 .
  6. 6. The method of assessing the pozzolan activity of bayer process red mud according to claim 1, wherein the bayer process red mud has a main chemical component of 26.39wt.％CaO、25.71wt.％Fe 2 O 3 、17.77wt.％Al 2 O 3 、15.06wt.％SiO 2 、6.83wt.％TiO 2 and 5.91wt.% Na 2 O.
  7. 7. The method for evaluating the pozzolan activity of bayer process red mud according to claim 1, wherein the calcination temperature is 500-900 ℃.
  8. 8. The method for evaluating the pozzolan activity of bayer process red mud according to claim 1, wherein the incubation time is 2h.
  9. 9. The method for evaluating the pozzolan activity of bayer process red mud according to claim 1, wherein the heating rate is 5 ℃.

Description

Evaluation method for activity of red mud volcanic ash by Bayer process Technical Field The invention relates to the technical field of cement and concrete, in particular to a method for evaluating the activity of Bayer process red mud pozzolan. Background Cement concrete is a support for the development of modern society and is also a key building material for important national strategic projects. Global cement production continues to increase from 36.03 billion tons in 2010 to 41.63 billion tons in 2022. From the cement production data of the main cement producing country in the world of 2022, china is in the top of 21.30 million tons of production, accounting for 51.2% of the global total production. The CO 2 emissions from the cement industry account for 8% of the total emissions worldwide, with about 40% of the emissions coming from the calcification process of limestone in the cement raw material. These large amounts of CO 2 emissions create a significant pressure on the ecological environment. Thus, to accommodate the time demand for green production, the cement industry needs to be continually upgraded and updated. One widely accepted method is to introduce industrial waste residues in the production of concrete to replace the cement in part. The cement has low cement consumption, and some industrial waste slag may be used as supplementary cementing material to react with cement hydration product to form secondary hydration product to raise the compactness of cement stone, improve certain performance of concrete and prolong the service life. Meanwhile, bayer process Red Mud (RM) is pollution waste residue generated after alumina is extracted from bauxite, and 0.8-2 tons of red mud is generated along with each 1 ton of alumina. Annual production of 2022 chinese alumina was found to be 7976 ten thousand tons accounting for 57.4% of the global total production. However, the annual emission of RM exceeds 1 hundred million tons, and the accumulated storage amount exceeds 10 hundred million tons, but the comprehensive utilization rate is only less than 10%. The RM processing and comprehensive utilization rate is far lower than the development rate of the alumina industry. RM has high alkalinity and complex composition, and contains heavy metal ions with radiation, and large-scale stockpiling causes great harm to the environment. To solve the RM pollution problem, comprehensive utilization of RM has become an important focus of attention of researchers. The RM has main chemical components including CaO, siO 2、Al2O3, fe 2O3 and other elements, and also contains some amorphous aluminosilicate. By mixing RM with a proper amount of limestone, sandstone, etc., various types of cements can be prepared during sintering. In addition, RM also has certain gelling activity and can be used as an active mixed material of cement. The use of RM as a concrete admixture enables the production of concrete materials with strength and durability required for engineering applications. The method not only effectively relieves various pollution problems caused by RM stockpiling and realizes effective utilization of RM resources, but also obviously reduces energy consumption in cement and concrete production processes, and has obvious environmental and economic advantages. However, current RM applications in cement materials are relatively low due to its high alkalinity and low pozzolanic activity. The pozzolanic activity of RM is a hot topic of current research. The composition of RM is affected by bauxite ore and production process, so there is a large difference in RM composition from region to region. On the other hand, there is currently no established method to accurately and scientifically evaluate the activity of RM materials of different types and properties. How to more effectively and scientifically utilize RMs with different activities has important significance in the field of building materials. Therefore, the design of a scientific and reasonable RM activity evaluation method is helpful for realizing the efficient utilization of red mud resources in cement-based materials, and the targeted research of activity excitation technology and hydration mechanism. Over the last decades, scholars have proposed various methods for assessing RM pozzolan activity. Some methods are proposed based on the principle of interaction between calcium hydroxide and red mud. In addition, several simple, rapid and quantitative methods have been used to evaluate the pozzolanic activity of RMs, including analysis of their chemical composition, their crystallinity of minerals, and their strength and electrochemical properties. Although the intensity evaluation method can reflect the overall pozzolanic activity of the RM comprehensively and intuitively, a longer test period is generally required. Dissolution assessment methods require separation of the active component from the inert component under appropriate conditions. However, the impl