KR101937620B1 - Cement mixture and manufacturing method thereof - Google Patents

Abstract

The present invention relates to cement additives, in which hexavalent chromium generated in cement is eliminated, and at the same time, the strength and inherent physical properties of cement are maintained, and to a manufacturing method thereof. In addition, the cement additives of the present invention can be used for treatment of wastewater of cement, concrete, mortar sewage or improvement of soil.

Description

TECHNICAL FIELD [0001] The present invention relates to a cement admixture,

The present invention relates to a cement additive which removes hexavalent chrome (Cr ⁶⁺ ) generated from cement and maintains strength and inherent physical properties of the cement, and a method for producing the same.

Cement is a mineral binder with the property of bonding materials and materials. It is a mineral fine powder that solidifies by reacting with water, and is used as a mixture used to build a building.

Cement is largely divided into portland cement, white portland cement and blended cement.

Among them, Portland cement is produced by mixing raw materials containing the main components of lime, silica, alumina and iron oxide at appropriate ratios, melting a part thereof, and putting an appropriate amount of gypsum into a sintered clinker.

In Korea, the use of calcined limestone is recorded in 'Sejong Silok Gejije', and it is recorded that it was used for the construction of the wall in 'Bukhak' of Jejak Street.

In the 1960s and 1980s, cement was manufactured from limestone as a raw material due to its geographical characteristics, which are rich in limestone.

However, since the 1990s, cement has been manufactured using industrial wastes as an additive or substitute raw material in an annual amount of 3 to 4 million tons during the manufacturing process for cost reduction and industrial waste disposal.

Industrial wastes were used for raw materials such as steel slag, incineration ash, dyed sludge, chemical waste sludge, and waste semiconductors.

In addition, cement containing industrial wastes was caused by diseases such as atopy, sick house syndrome and the like due to carcinogens such as hexavalent chromium.

Hexavalent chromium is a non-metallic primary carcinogen. It has a strong oxidizing action and is toxic. It causes various cancers and diseases such as skin cancer and lung cancer through contact or inhalation.

In advanced countries such as Europe and Japan, hexavalent chromium is regulated at 2mg / kg, but in Korea, it is regulated at less than 20mg / kg.

In recent years, research and development are underway to lower the hexavalent chromium level in order to manufacture safe cement, which has improved problems such as harmful and carcinogenic substances, rather than cost reduction.

BACKGROUND ART [0002] As a prior art which becomes the background art of the present invention, Korean Patent Laid-Open Publication No. 10-2006-0036459 (hereinafter referred to as "Prior Art 1"), Korean Patent Laid- Korean Patent Registration No. 10-0849395 (hereinafter referred to as "Prior Document 3") and Japanese Patent Laid-Open No. 2008-308396 (hereinafter referred to as "Prior Document 4").

Prior Art 1 is a reducing agent for soluble chromate content in cement and a reducing agent for reducing hexavalent chromium by mixing iron sulfate compound with cement.

However, iron sulfate compounds mixed in cement are not suitable for use as a hexavalent chromium reductant because mercury is generated during the manufacturing process or during use, Do.

Prior Art 2 is a composition using a non-lignosulfonate-based complexing agent for stably increasing hexavalent chromium reduction with a hexavalent chromium reducing composition in cement.

The invention of the prior art document 2 uses tin sulfate and sodium gluconate in combination with cement in an aqueous environment but after about 26 days the hexavalent chromium is reoxidized and the amount of hexavalent chromium oxidized over time This is inadequate to use in environments where people live.

Prior Art 3 is a cement hexavalent chromium reducing agent having excellent oxidation stability, which is a hexavalent chromium reducing agent which effectively reduces the hexavalent chromium content in cement production and storage by mixing a hexavalent chromium reducing agent and zeolite.

The invention of the prior art document 3 uses cement as a reducing agent by mixing ferrous sulfate, tin sulfate, tin chloride, zinc chloride and zeolite, but the content of hexavalent chromium in the cement is 10 to 18 ppm, This is also unsuitable for use in a human residential environment.

Prior art 4 is a pollution-free water-resistant treatment body which exhibits functions of hydration, fixation, binding, hardening and water-resistance at room temperature with a water composition, a utilization treatment method and a pollution-free water resistance treatment composition.

The invention of the prior art document 4 is used as a charcoal-silicate bearing material containing silica and alumina having adsorption capability, but it is difficult to mix it with cement because it mainly purifies water.

Accordingly, the present applicant has found that a cement additive in which hexavalent chromium is not oxidized without using iron sulfate is reduced to hexavalent chromium.

<Prior Art Literature>

Korean Patent Publication No. 10-2006-0036459

Korean Patent Publication No. 10-2008-0044246

Korean Patent Registration No. 10-0849395

Japanese Patent Application Laid-Open No. 2008-308396

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a cement additive for improving the problem of hexavalent chromium, which is a harmful and carcinogenic substance.

Also, the cement additive of the present invention is to provide the same strength and specific properties as the existing cement even when mixed before the cement production process or before the cement casting.

Further, the present invention is to reduce the production cost according to the diversity of the cement processing process.

Further, the cement additive of the present invention is to provide cement which can be introduced into wastewater treatment or soil improvement.

In particular, the cement additive of the present invention is to provide a cement wherein the cement is not oxidized to hexavalent chromium by heat and the reduced hexavalent chromium is not oxidized again over time.

In order to accomplish the above object, the present invention is a cement additive characterized by containing 15 to 25 parts of charcoal and 75 to 85 parts of iron chloride as parts by weight.

In addition, the present invention is characterized in that 15 to 25 parts of silicate and 75 to 85 parts of iron chloride are contained by weight.

The present invention is a cement mixture characterized in that 0.1 to 0.8 wt% of iron chloride is contained in the cement.

Also, the cement additive of the present invention is contained in the cement in an amount of 0.1 to 0.8 wt%.

The cement admixture of the present invention is characterized in that calcium stearate is further contained in an amount of 10 wt% or less.

The present invention provides a cement additive which improves the problems of harmful and carcinogenic substances, which is produced in a cement production method using waste, and thus has an effect of significantly reducing hexavalent chromium.

Also, the cement additive of the present invention has the effect of maintaining the same strength and specific properties as the existing cement even if mixed before the cement production process or before cement casting.

Further, the present invention is to reduce the production cost according to the diversity of the cement processing process.

Furthermore, the cement additive of the present invention can provide cement that can be introduced into wastewater treatment or soil improvement.

In particular, the cement additive of the present invention can provide a cement wherein the cement is not oxidized to hexavalent chromium by heat and the reduced hexavalent chromium is not oxidized again over time.

Figure 1 is a cement additive of the present invention.
FIG. 2 is a hexagonal chromium leaching test report of conventional cement.
3 and 4 are histograms of hexavalent chromium leaching test results of the cement containing the cement additive of the present invention.
FIG. 5 is a result of visual inspection of cement containing cement additive of the present invention and hexavalent chromium detection of commercially available cement.
6 is a photograph showing goldfish survival experiment using cement containing cement additive of the present invention and commercially available cement.
FIG. 7 shows the result of checking an anion value using cement containing the cement additive of the present invention and commercially available cement.
FIG. 8 shows the results of visual inspection of the detection of hexavalent chromium before and after heating using cement containing the cement additive of the present invention and commercially available cement.

Hereinafter, the present invention will be described in detail with reference to examples.

The objects, features and advantages of the present invention will be easily understood by the following embodiments.

The present invention is not limited to the embodiments disclosed herein, but may be embodied in other forms. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , &Lt; / RTI &gt; equivalents, or alternatives.

Therefore, it should be understood that the present invention should not be limited by the following embodiments, and all transformations included in the technical idea and technical scope of the present invention are included. That is, those skilled in the art will appreciate that various modifications, additions, substitutions, substitutions, improvements, additions, substitutions, additions, substitutions, additions, substitutions, additions, It will be understood that it is also within the scope of the invention.

The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated and described in the drawings. The sizes of the elements or the relative sizes between the elements in the figures may be exaggerated somewhat for a clear understanding of the invention. Further, the shape of the elements shown in the drawings may be somewhat modified by variations in the manufacturing process or the like.

Accordingly, the embodiments disclosed herein should not be construed as limited to the shapes shown in the drawings unless specifically stated, and should be understood to include some modifications.

On the contrary, the various embodiments of the present invention can be combined with any other embodiments as long as there is no clear counterpoint. Any feature that is specifically or advantageously indicated as being advantageous may be combined with any other feature or feature that is indicated as being preferred or advantageous. That is, various aspects, features, embodiments, or implementations of the invention may be used singly or in various combinations.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting as to the scope of the claims, and all technical and scientific terms used herein have the same meanings as commonly understood in the art Has the same meaning as is generally understood by a person with. The singular expressions include plural expressions unless the context clearly dictates otherwise.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

&Lt; Example 1 >

The cement additive of the present invention can contain charcoal and iron chloride in order to reduce hexavalent chromium to trivalent chromium and not to be oxidized again over time. Alternative materials can be used due to discontinuation of production, economic problems or toxicity problems Therefore, the present invention is not limited thereto.

More specifically, the cement additive may include 15 to 25 parts of charcoal and 75 to 85 parts of iron chloride, and preferably 18 to 22 parts of charcoal and 78 to 82 parts of iron chloride, and most preferably 20 parts of charcoal, 80, but the present invention is not limited thereto.

The iron chloride may be iron chloride tetrahydrate, but is not limited thereto.

In addition, the cement additives can be prepared by mixing in a conventional manner.

Further, the cement additives may be in the form of powder or an aqueous solution, preferably in powder form, but are not limited thereto.

The char is excellent in adsorption ability due to a large number of micropores, and is used by adsorbing reduced hexavalent chromium and keeping it in a deactivated state.

The charcoal used in the present invention may be any one or more of pine wood charcoal, bamboo charcoal, oak charcoal, and ginkgo char, preferably bamboo charcoal or oak charcoal, more preferably Oak charcoal may be used, but is not limited thereto.

In addition, the char used in the present invention may be in powder form, but is not limited thereto.

The pore diameter of charcoal depends on the type of wood used. The mean diameter of pores is 1 ~ 10㎛ for pine charcoal, 3 ~ 15㎛ for bamboo charcoal, 2 ~ 10㎛ for oak charcoal, and 3 ~ 10㎛ for ginkgo charcoal.

Oak oak charcoal may be used at an intermediate temperature of 500 to 900 ° C or at a high temperature of 1,100 to 1,300 ° C, but is not limited thereto.

In addition, the micro pore water of the oak charcoal is most preferably the one which contains much of the coal which is eaten at a higher temperature than the middle temperature and is eaten at a high temperature, but is not limited thereto.

In particular, unlike other charcoal, oak charcoal has a lot of fine pores and has excellent adsorption ability, and has an excellent effect for removing hexavalent chromium.

The bamboo charcoal may be obtained by agglomerating at a high temperature of 1,000 ° C or higher, preferably at 1,100-1,300 ° C, but is not limited thereto.

In particular, bamboo charcoal has an excellent effect on the adsorption rate when it is used for removing heavy metals, and has negative ion, far infrared ray, electromagnetic wave shielding, odor removal and air purification, water purification, antibacterial and detoxification, mineral supply and humidity control.

The iron chloride tetrahydrate were deliquescent the crystal specific gravity is soluble in water and alcohol to 1.926g / cm ³ as in a light green, to decompose the hydrate and heat in the air is the iron oxide (Fe ₂ O _3).

In the present invention, iron chloride causes the reaction of chromium reduction by the electron supply, Fe ^{2 +} , so that hexavalent chromium is reduced to trivalent chromium.

&Lt; Example 2 >

The cement additive of the present invention may contain silicate and iron chloride to reduce hexavalent chromium to trivalent chromium and not be oxidized again over time, and substitute materials may be used due to discontinuation of production, economic problems or toxicity problems Therefore, the present invention is not limited thereto.

More specifically, the cement additive may include 15 to 25 parts by weight of silicate and 75 to 85 parts by weight of iron chloride, preferably 18 to 22 parts by weight of silicate and 78 to 82 parts by weight of iron chloride, most preferably 20 parts by weight of silicate, 80, but the present invention is not limited thereto.

The iron chloride may be iron chloride tetrahydrate, but is not limited thereto.

In addition, the cement additives can be prepared by mixing in a conventional manner.

Further, the cement additives may be in the form of powder or an aqueous solution, preferably in powder form, but are not limited thereto.

The silicate is a compound containing anions in which one or more silicon central atoms are surrounded by a negatively charged ligand, which further enhances corrosion resistance.

The silicate used in the present invention neutralizes cations of heavy metals by using anions and has a pore structure to adsorb the reduced hexavalent chromium and maintain its deactivated state by coating its periphery.

The iron chloride causes the reaction of chromium reduction by the electron supply, Fe ^{2 +} , so that hexavalent chromium is reduced to trivalent chromium.

&Lt; Example 3 >

The cement admixture of the present invention means a mixture of cement and cement additives.

The cement additive may be selected from the group consisting of iron chloride, cement additive of Example 1, and cement additive of Example 2.

The iron chloride may be iron chloride tetrahydrate, but is not limited thereto.

In addition, the cement additive may be mixed before cement production or before cementing to provide the same strength and inherent physical properties as existing cement, but is not limited thereto.

The cement admixture may contain 0.1 to 0.8% by weight, preferably 0.2 to 0.7% by weight, more preferably 0.3 to 0.6% by weight of the cement additive in the cement in order to insure or reduce the hexavalent chromium contained in the cement But is not limited thereto.

If the cement additive is contained in the cement at less than 0.1 wt%, the hexavalent chromium can be detected in a very small amount, and if the cement additive is contained at more than 0.8 wt%, the inherent property of the cement can be changed.

In addition, when the cement additive is contained in less than 0.2 wt% of cement, a small amount of hexavalent chromium can be detected, and when the cement additive is contained in excess of 0.7 wt%, the strength of the cement can be changed.

In addition, the cement additive may be used for cement, concrete, mortar wastewater treatment or soil improvement, but is not limited thereto.

In order to further increase the strength of the cement in the present invention, the cement admixture may further contain calcium stearate in an amount of 10 wt% or less, preferably 1 to 6 wt%, more preferably 2 to 5 wt%, and most preferably 2 By weight to 3% by weight.

Since the calcium stearate has a property of not absorbing water, the strength of the cement can be improved due to the improved water repellency and waterproofness.

Also, when calcium stearate is mixed in the cement mixture in an amount of more than 10% by weight, the strength development may be lowered.

Further, when calcium stearate is mixed at less than 2% by weight in the cement mixture, the effect of water repellency and waterproofing may be insignificant. If the calcium stearate is mixed at more than 3% by weight, the production cost may be increased and it may not be economical.

<Experimental Example 1>

Experiments were performed to compare cement containing cement additives prepared from the examples of the present invention with hexavalent chromium of conventional cement.

Experimental group A contained 0.5% by weight of cement additive containing charcoal and iron chloride in cement. In experiment group B, 0.5% by weight of iron chloride was contained in cement.

The control group used cement containing commercially available iron sulfate.

For the hexavalent chromium dissolution test, KS L 5221: 2017 test method was used.

Table 1 below summarizes the results of the hexavalent chromium dissolution test.

Experimental group A Experimental group B Control group Hexavalent chromium (mg / kg) 2.7 7.4 24.3

As shown in Table 1 and FIG. 2 to 4, in the experimental group A, 2.7 mg / kg of hexavalent chromium, 7.4 mg / kg in the experimental group B, and 24.3 mg / kg in the control group were detected.

Compared with experimental groups A and B, it can be seen that the use of cement additives reduces the amount of hexavalent chromium by 3.3 ~ 9 times.

Therefore, when the cement additive used in the present invention is mixed with cement, a small amount of hexavalent chrome is eluted to a concentration of less than 8 mg / kg, and it can be confirmed that a very small amount of the hexavalent chromium elutes to less than 3 mg / kg depending on the material used.

In addition, it can be deduced that the reduced hexavalent chromium is not oxidized again after a certain period of time because the cement additive does not use iron sulfate.

<Experimental Example 2>

Experiments were carried out to visually confirm the cement additive prepared on the basis of the examples of the present invention and the hexavalent chromium generated in the commercially sold cement.

Experimental group A used cement containing cement additive containing charcoal and iron chloride. Experiment group B used cement containing cement additive containing silicate and iron chloride.

The control group used cement containing commercially available iron sulfate.

Table 2 below shows the degree of redness (++: high, +: low, -: none) with visual confirmation of hexavalent chromium dissolution.

Experimental group A Experimental group B Control group Hexavalent chromium detection - - ++

As shown in Table 2 and FIG. 5, it was visually confirmed that hexavalent chromium was not detected through the transparent sample of the test groups A and B.

On the other hand, the sample of the control group was reddish and visually confirmed that hexavalent chromium was detected.

Therefore, it can be confirmed that hexavalent chromium is not detected when the cement additive of the present invention is used for cement.

<Experimental Example 3>

The goldfish survival experiment was performed using the cement containing the cement additive manufactured on the basis of the embodiment of the present invention and the conventional cement.

As shown in Fig. 6, the cement of the experimental group and the control cement were submerged in the specimens to confirm the survival of the goldfish.

Cements containing 0.3, 0.4, 0.5 and 0.6% by weight of the cement additives prepared on the basis of the examples were used for the test groups A, B and C, respectively. Cements sold in the market were used as a control group.

In experiment group A, cement additive containing charcoal and iron chloride was used for cement, and cement additive containing silicate and ferric chloride was used for experimental group B.

In experiment C, cement containing iron chloride was used.

Table 3 shows the goldfish survival test results.

Experimental group A Experimental group B Experimental group C Control group Goldfish survival Good health Good health Good health Approximately 8 hours

As shown in Table 3, the goldfish in the experimental group A to C survived, but the goldfish in the control group became dull after 4 hours, and all the goldfishes died after about 8 hours.

It was also confirmed that goldfish survived regardless of changes in contents of cement additives in experimental group.

Therefore, it can be deduced that the cement containing the cement additive of the present invention does not release hexavalent chromium.

<Experimental Example 4>

Experiments were conducted to confirm the anion level by using cement containing cement additive manufactured on the basis of an embodiment of the present invention and commercially available cement.

The experimental group used cement containing the cement additive prepared on the basis of the examples, and the control group used cement sold on the market.

7, it was confirmed that the anions of the experimental group were 280-285 ions / cc and the average was 283 ions / cc, and the anion of the control group was 60 ions / cc.

In addition, the anion of the experimental group has about 5 times anion when compared with the anion of the control group.

In particular, the anion of the experimental group is 283 ions / cc, which is similar to that in the forest when compared to the anion value of 280 ~ 300 ions / cc generated in the forest.

<Experimental Example 5>

Experiments were conducted to compare the elution of hexavalent chromium after heating using cement containing a cement additive manufactured on the basis of the examples of the present invention.

The experimental group was classified into A, B and C by using the cement additives of the examples, and only the commercially available cement was used as the control group.

Experimental group A consisted of cement additive containing charcoal and iron chloride. Experimental group B contained cement additive containing silicate and iron chloride. Experiment group C was iron chloride.

Experimental method of hexavalent chromium dissolution after heating First, it is confirmed that hexavalent chromium is detected by adding cement to each beaker containing distilled water.

The cement is the same as the cement used in the control group.

Thereafter, except for the beaker of the control group, the addition of the cement additive to the beaker of the experimental group containing the cement is confirmed to confirm the presence of hexavalent chromium.

Finally, each beaker was heated in an oven at 105 ° C for 3 to 4 minutes, and then the presence of hexavalent chromium was detected.

Table 4 below shows the results of confirming whether or not hexavalent chromium is eluted before and after heating (O: detected, X: not detected).

Whether 6 is chrome Experimental group A Experimental group B Experimental group C Control group Before heating X X X O After heating X X X O

As shown in Table 4 and FIG. 8, it was confirmed that no hexavalent chromium was detected before and after heating the test groups A to C, and that the control group detected hexavalent chromium before and after heating the sample.

It can be deduced that the cerium additive of the present invention or hexavalent chromium reduced by the iron chloride is a heat-stable structure.

In particular, cement contains a calcining process, but the above results show that even if cement additives are included in the entire cement production cycle, the hexavalent chromium reduced by heat is not reoxidized.

<Experimental Example 6>

Experiments were conducted to confirm the removal efficiency of hexavalent chromium by preparing a cement admixture as a cement admixture as in Example 3 based on the examples of the present invention.

Table 5 below shows the results of confirming the removal efficiency of hexavalent chromium (?: Best,?: Good,?: Normal).

Charcoal + ferric chloride Silicate + ferric chloride Ferric chloride Hexavalent chromium removal efficiency ◎ ○ ○

As shown in Table 5, the removal efficiency of hexavalent chromium was the highest when cement additive containing charcoal and iron chloride was used, followed by the use of cement additive containing silicate and chloride, The time was good.

INDUSTRIAL APPLICABILITY The present invention is an industrially applicable invention for a cement additive in which the hexavalent chromium generated from cement is removed and the strength and inherent physical properties of the cement are maintained, and a method for producing the same.

Claims (6)

Characterized in that the ferric chloride tetrahydrate is contained in the cement in an amount of 0.1 to 0.8% by weight, so that the hexavalent chromium content is 20 mg / kg or less when made of concrete or mortar. The method according to claim 1,
Characterized in that it further comprises not more than 10% by weight of calcium stearate. A mortar comprising the cement admixture of claim 1 or 2. A concrete comprising the cement admixture of claim 1 or 2. A wastewater treatment improving agent comprising the cement admixture of claim 1 or 2. A soil remediation agent comprising the cement admixture of claim 1 or 2.

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