KR20230093138A - Pozzolan cement composition and method for preparing the same - Google Patents

Abstract

According to one aspect of the present invention, drying a lithium extraction process by-product containing an aluminosilicate compound (Al-Si-O); Powdering the dried by-product; Preparing a siliceous mixture by mixing the powdered by-product with silica sand powder or silica fume; and mixing the siliceous mixture with Ordinary Portland Cement in a weight ratio of 3:7 to 1:9. According to another aspect of the present invention, 70 to 90% by weight of at least one selected from the group consisting of ordinary Portland cement and clinker; And 10 to 30% by weight of a siliceous mixture containing a lithium extraction process by-product containing an aluminosilicate compound (Al-Si-O); a pozzolan cement composition is provided. According to the present invention, it is possible to economically obtain pozzolan cement having improved compressive strength and reduced shrinkage cracking by utilizing by-products generated in the lithium extraction process.

Description

Pozzolan cement composition and method for preparing the same {Pozzolan cement composition and method for preparing the same}

The present invention relates to a pozzolan cement composition prepared by utilizing an alumino-silicate compound, which is a residual by-product after extracting lithium from lithium ore, and a method for preparing the same.

The importance of lithium as a material for secondary batteries and as a power source for hybrid and electric vehicles has recently emerged, and the future market size is expected to grow by 50 to 100 times compared to the present.

In general, lithium can be extracted from ores containing lithium, and lithium exists as a mineral phase called LiAlSi ₂ O ₆ (Spodumene) in lithium-containing ores.

Since this lithium exists in the dense form of α-phase, in order to extract lithium from lithium ore, as in Patent No. 10-2307918, a technique of converting it to β-phase and then leaching it with sulfuric acid and extracting it has been developed. there is.

In a series of processes for recovering lithium from lithium ore, spodumene (LiAlSi ₂ O ₆ ), the main mineral phase of lithium ore, is ion-exchanged with H ⁺ ions dissociated from sulfuric acid at the Li ⁺ ion site of the ore by the sulfuric acid roasting process. , ion-exchanged Li ⁺ ions combine with dissociated SO ₄ ^2- ions, and a precipitation reaction proceeds to precipitate lithium sulfate (Li ₂ SO ₄ ).

When the precipitated lithium sulfate (Li ₂ SO ₄ ) is leached with water and then solid-liquid separated, lithium sulfate and residual by-products remain.

That is, lithium sulfate (Li ₂ SO ₄ ) is dissolved in water and leached out, while aluminosilicate (Al ₂ O ₃ 4SiO ₂ , AlSi ₂ O ₆ ) is insoluble in water and remains in the form of a solid compound. .

Lithium in lithium ore contains about 2 to 3%, so a significant amount of gangue remains after lithium extraction. For example, after handling 200,000 tons of lithium ore and extracting 2-3% of lithium from it, 70-80% of residual by-products remain.

As a domestic and foreign technology, the technology to extract lithium from lithium concentrate is actively being developed, but research cases for recycling by-products after lithium extraction are insufficient.

Accordingly, if a method for economically recycling by-products after lithium extraction is provided, it is expected to be useful in related fields.

The present invention relates to a pozzolanic cement composition and a method for preparing the same, wherein a pozzolanic hydrate can be formed by mixing lithium extraction process by-products including an aluminosilicate compound with silica sand powder or silica fume, thereby preparing cement having excellent compressive strength. An object of the present invention is to provide a pozzolanic cement composition and a method for preparing the same.

According to one aspect of the present invention, drying a lithium extraction process by-product containing an aluminosilicate compound (Al-Si-O); Powdering the dried by-product; Preparing a siliceous mixture by mixing the powdered by-product with silica sand powder or silica fume; and mixing the siliceous mixture with Ordinary Portland Cement in a weight ratio of 3:7 to 1:9.

According to another aspect of the present invention, 70 to 90% by weight of at least one selected from the group consisting of ordinary Portland cement and clinker; And 10 to 30% by weight of a siliceous mixture containing a lithium extraction process by-product containing an aluminosilicate compound (Al-Si-O); a pozzolan cement composition is provided.

According to the present invention, it is possible to economically obtain pozzolan cement having improved compressive strength and reduced shrinkage cracking by utilizing by-products generated in the lithium extraction process.

Figure 1 shows the XRD results of by-products generated in the lithium extraction process of the present invention.
Figure 2 shows the results of measuring the compressive strength of the pozzolan cement prepared in Examples 1 to 12 and Comparative Examples 1 to 4.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified in various forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to a pozzolanic cement composition and a method for preparing the same.

Specifically, according to one aspect of the present invention, drying the by-product of the lithium extraction process containing an aluminosilicate compound (Al-Si-O); Powdering the dried by-product; Preparing a siliceous mixture by mixing the powdered by-product with silica sand powder; and mixing the siliceous mixture with Ordinary Portland Cement in a weight ratio of 3:7 to 1:9.

The by-product of the lithium extraction process may mean a residual by-product after extracting lithium from a lithium concentrate, which is a lithium-containing ore, and may mean, for example, alumino-silicate in the form of a solid compound.

As can be seen from the XRD of FIG. 1, the by-products of the lithium extraction process of the present invention are H(Al·SiO ₂ )O ₆ (50.9%), SiO ₂ (6.7%), Ca(SO ₄ ) as shown in Table 1 below. 2H ₂ O (22.6%), H(Al Si ₂ O ₆ ) (11.2%), Li ₂ (SO ₄ ) H ₂ O (3.1%), (Ca _0.94 Na _0.06 )Al ₂ Si ₂ O ₈ (5.4%) and the like.

CaO SiO ₂ Al ₂ O ₃ MgO Fe ₂ O ₃ SO _{3 K2O} moisture Lithium extraction process by-product 3.27 57.7 21.4 0.35 1.07 7.05 0.9 5-10%

Since the lithium-containing ore undergoes a sulfuric acid roasting process during the lithium extraction process, the by-product may include a crystal phase of Li ₂ (SO ₄ ) H ₂ O, and in order to purify impurities in the process of dissolving and leaching lithium sulfate with water By adding calcium hydroxide (Ca(OH) ₂ ) to adjust the pH, a Ca(SO ₄ )·2H ₂ O crystal phase may be included.

H ₂ SO ₄ +Ca(OH) ₂ →Ca(SO ₄ )·2H ₂ O

In addition, the by-product mainly consists of aluminosilicate crystal phases, H(Al·SiO ₂ )O ₆ and H(Al·Si ₂ O ₆ ), and may include about 62% of the total crystal phase.

Since the by-product may have a moisture content of 25 to 35% through a wet process, a step of drying to a moisture content of 3% or less may be performed. If the moisture content is more than 3%, there is a problem that powdering is not easy due to excessive moisture, and if it is less than 3%, it can be sufficiently dried by heat generated by friction of equipment in the powdering process.

A step of pulverizing the dried by-product may be performed, and specifically, a step of pulverizing to a powder degree of 2,000 to 5,000 cm ² /g may be performed. For powdering, a ball mill, roller mill, Roche mill, etc. may be used, but any method capable of powdering the powder at a concentration of 2,000 to 5,000 cm ² /g may be used without limitation.

When the powder fineness is less than 2,000 cm ² /g, it is difficult to induce a hydration reaction when used in cementitious materials, and when the powder fineness exceeds 5,000 cm ² /g, the specific surface area increases excessively, so water is used to secure fluidity. There is a problem in that an excessive amount of the mixture is required or the curing speed becomes excessively fast after mixing water. When the powder size is within the range of 2,000 to 5,000 cm ² /g, it is possible to secure appropriate fluidity, which makes it easy to secure working time. occurrence can be prevented, and the occurrence of a side effect of lowering strength can be reduced.

Thereafter, a siliceous mixture may be prepared by mixing the powdered by-product with silica sand powder or silica fume. Silica fume refers to fine dust generated in the manufacturing process of FeSi (ferro silicon), etc., and since silica powder or silica fume is a typical SiO ₂ rich material, mixing it with by-products increases the SiO ₂ content of the siliceous mixture. can increase In more detail, as shown in Table 1, the SiO ₂ content of the by-product of the lithium extraction process is about 57.7%, but the SiO ₂ content of silica powder or silica fume is usually about 90% or more, so that the SiO 2 content is 60% or more by mixing it. A siliceous mixture having a content of ₂ can be prepared.

When the siliceous mixture is mixed with cement, Ca ²⁺ ions originating from the cement react with Si ⁴⁺ ions originating from the aluminosilicate compound, so that xCaO-ySiO ₂ -zH ₂ O (calcium silicate) or xCaO- Pozzolanic hydrates such as yAl ₂ O ₃ -zSiO ₂ -oH ₂ O (calcium aluminosilicate) can be formed.

In addition, Ca ²⁺ and Al ³⁺ ions derived from cement react with Al ³⁺ ions derived from aluminosilicate compounds to form 3CaO·Al ₂ O ₃ 3CaSO ₄ 32H ₂ O (ettringite). Can form hydrates.

When the siliceous mixture of the present invention and cement react to form the pozzolanic hydrate, the strength of the cement is improved, shrinkage is reduced, and carbon dioxide generated by about 0.8 tons per ton during cement production can be reduced in large quantities. can

Table 2 below shows SiO ₂ and SO ₃ contents of the siliceous mixture according to the weight ratio of the lithium extraction process by-product and the silica powder or silica fume of the present invention.

division Mixed weight ratio (%) Sum(%) of siliceous mixtures
SiO ₂ content
(%) of siliceous mixtures
SO ₃ content
(%) Lithium extraction process by-product
(SiO ₂ : 57.7%) silica sand powder
(SiO ₂ : 93%)
or silica fume One 100 0 100 57.7 7.05 2 95 5 100 59.465 6.7275 3 90 10 100 61.23 6.405 4 85 15 100 62.995 6.0825 5 80 20 100 64.76 5.76

When the SiO ₂ content of the siliceous mixture is 55 to 65% and the SO ₃ content is 5 to 8%, pozzolanic hydrate may be easily formed.

Furthermore, the siliceous mixture may be mixed with Ordinary Portland Cement to prepare pozzolanic cement. The pozzolan cement is a cement specified in the national standard KS L 5401 and can be classified into 1, 2, and 3 types, and more specifically, more than 5 parts by weight of a siliceous mixture based on 100 parts by weight of ordinary Portland cement or clinker 10 parts by weight It can be classified as including the following (1 type), 10 to 20 parts by weight or less (2 types), and 20 to 30 parts by weight or less (3 types). Therefore, when mixing, the siliceous mixture and ordinary Portland cement may be mixed in a weight ratio of 30:70 to 5:95, preferably 30:70 to 10:90.

In addition, the pozzolan cement may additionally include anhydrite (CaSO ₄ ) or dihydrate gypsum (CaSO ₄ ·2H ₂ O). When the gypsum is included, SO ₃ eluted from the gypsum may generate the ettringite hydrate.

Hereinafter, the present invention will be described in more detail through specific examples. The following examples are merely examples to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

The by-product of the lithium extraction process was pulverized to a powder degree of 3400 cm ² /g using a ball mill. Then, silica powder was mixed in a weight ratio as shown in Table 3 to prepare a siliceous mixture, and its SiO ₂ content was measured.

division Lithium extraction process by-product
(wt%) silica sand powder
(wt%) SiO ₂ content
(%) Preparation Example 1 95 5 59.465 Preparation Example 2 90 10 61.23 Preparation Example 3 85 15 62.995 Production Example 4 80 20 64.76 Comparative Preparation Example 1 100 0 0

Pozzolanic cement (KS L 5401) was prepared by mixing the siliceous admixture Comparative Example 1 and the siliceous admixture Preparation Examples 1 to 4 with ordinary Portland cement.

division Silica mixture (by-product: silica sand powder) Silica mixture
(wt%) plain portland cement
(wt%) 3 kinds of pozzolan cement Example 1 Preparation Example 1 (95:5) 30 70 Example 2 Preparation Example 2 (90:10) 30 70 Example 3 Preparation Example 3 (85:15) 30 70 Example 4 Preparation Example 4 (80:20) 30 70 Comparative Example 1 Comparative Preparation Example 1 (100:0) 30 70 2 kinds of pozzolan cement Example 5 Preparation Example 1 (95:5) 20 80 Example 6 Preparation Example 2 (90:10) 20 80 Example 7 Preparation Example 3 (85:15) 20 80 Example 8 Preparation Example 4 (80:20) 20 80 Comparative Example 2 Comparative Preparation Example 1 (100:0) 20 80 1 type of pozzolan cement Example 9 Preparation Example 1 (95:5) 10 90 Example 10 Preparation Example 2 (90:10) 10 90 Example 11 Preparation Example 3 (85:15) 10 90 Example 12 Preparation Example 4 (80:20) 10 90 Comparative Example 3 Comparative Preparation Example 1 (100:0) 10 90 Comparative Example 4 - - 100

Using the cements of Examples 1 to 12 and Comparative Examples 1 to 4, water:cement:ISO standard sand was mixed at a weight ratio of 0.5:1:3 to prepare test specimens, and strength was evaluated. The strength evaluation method was evaluated according to the "strength test method of cement (KS L ISO 679)", and the strength at 28 days and 91 days after manufacture was measured and shown in Table 5 below. Six specimens were measured on each measurement day, and the average value was recorded as compressive strength.

division 28 days 91 days 3 kinds of pozzolan cement Example 1 46.4 53.9 Example 2 46.7 56.8 Example 3 47.4 57.9 Example 4 48.8 59.4 Comparative Example 1 40.7 48.4 2 kinds of pozzolan cement Example 5 47.4 54.7 Example 6 48.7 54.9 Example 7 49.7 55.1 Example 8 50.7 55.8 Comparative Example 2 42.0 50.1 1 type of pozzolan cement Example 9 48.4 54.2 Example 10 48.9 54.8 Example 11 50.1 55.7 Example 12 51.2 55.9 Comparative Example 3 45.7 51.4 Comparative Example 4 46.1 53.8

As shown in Table 5 and FIG. 2 below, in each of 1 to 3 types of pozzolan cement, the compressive strength of the example was significantly superior to that of the comparative example.

Comparative Examples 1 to 3 are cements prepared using Comparative Preparation Example 1 containing only lithium extraction process by-products without using silica sand powder, and Examples 1 to 12 are siliceous cements of Preparation Examples 1 to 4 containing silica sand powder. Since the cement is manufactured using a mixed material, the content of SiO ₂ is higher, and pozzolanic hydrate can be easily formed.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and variations are possible without departing from the technical spirit of the present invention described in the claims. It will be obvious to those skilled in the art.

Claims (10)

Drying a by-product containing an aluminosilicate compound (Al-Si-O) generated in a lithium extraction process;
Powdering the dried by-product;
Preparing a siliceous mixture by mixing the powdered by-product with silica sand powder, silica fume, or a mixture thereof; and
Mixing the siliceous mixture with Ordinary Portland Cement in a weight ratio of 3:7 to 1:9;
Method for producing a pozzolan cement composition comprising a.
According to claim 1,
The by-product further comprises at least one selected from the group consisting of H ₂ SO ₄ , CaSO ₄ , Al ₂ O ₃ , SiO ₂ , CaO and SO ₃ .
According to claim 1,
The powdering step is to powder the specific surface area (Blaine) of the by-product of the lithium extraction process to 2000 to 5000 cm ² /g, a method for producing a pozzolan cement composition.
According to claim 1,
SiO ₂ content of the siliceous mixture is 55% to 65%, a method for producing a pozzolan cement composition.
According to claim 1,
The SO ₃ content of the siliceous mixture is 5% to 8%, a method for producing a pozzolan cement composition.
According to claim 1,
A method for producing a pozzolan cement composition, wherein the weight ratio of by-products and silica sand powder or silica fume is 95:5 to 80:20 based on the total weight of the siliceous mixture.
According to claim 1,
A method for producing a pozzolan cement composition, wherein the by-product contains 60% by weight or more of an aluminosilicate compound (Al-Si-O) based on the total weight of the by-product.
10 to 30% by weight of a siliceous mixture containing a lithium extraction process by-product containing an aluminosilicate compound (Al-Si-O) and silica powder or silica fume; and
usually 70 to 90% by weight of Portland cement, clinker or mixtures thereof;
A pozzolan cement composition comprising a.
The by-product further comprises at least one selected from the group consisting of H ₂ SO ₄ , CaSO ₄ , Al ₂ O ₃ , SiO ₂ , CaO and SO ₃ .
A pozzolanic cement composition wherein the weight ratio of by-products and silica sand powder or silica fume is 95:5 to 80:20 based on the total weight of the siliceous mixture.

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