Preparation method of dustless damp-proof chalk

A technology of chalk and adsorbent, applied in the direction of pencil lead, household utensils, applications, etc., to achieve the effect of reasonable price

Inactive Publication Date: 2014-02-12
西安佳迅科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a preparation method of dust-free and moisture-proof chalk, which solves the problems in t

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0017] The preparation method of the dust-free and moisture-proof chalk of the present invention is implemented according to the following steps:

[0018] Step 1. Weigh the following components according to mass percentage, 45%-55% calcium carbonate, 45%-55% calcium sulfate (gypsum), 1%-2% clay, 2%-5% adsorbent, Total 100%.

[0019] Step 2: Heat the raw gypsum to a temperature of 60°-80° to partially dehydrate it to become mature gypsum, then add 10%-15% water to stir the plaster, and then add 45%-55% calcium carbonate and 1% -2% clay, 2%-5% adsorbent, stir together to form a paste, pour into the model to solidify to obtain a shaped chalk.

[0020] The reaction of green gypsum to mature gypsum (requires heating):

[0021] 2CaSO 4 ·2H 2 O=2CaSO 4 ·0.5H 2 O+3H 2 O

[0022] The reaction of adding water to gypsum plaster (normal temperature is sufficient):

[0023] 2CaSO 4 ·0.5H 2 O+3H 2 O=2CaSO 4 ·2H 2 O.

[0024] Step 3. Apply a layer of moisture-proof material (preferably paraffin) on th...

Example Embodiment

[0025] Example 1

[0026] Step 1. Weigh the following components according to the mass percentage, 45% calcium carbonate, 50% calcium sulfate (green gypsum), 2% clay, 3% adsorbent, totaling 100%.

[0027] Step 2: Heat the raw gypsum to 60°C to partially dehydrate it to become mature gypsum. Then add 10% water and stir the plaster of paris, then add calcium carbonate, 2% clay, and 3% adsorbent, and stir together to form Paste, pour into the model and solidify to get a shaped chalk.

[0028] Step 3, smear a layer of paraffin wax on the circumferential surface of the chalk obtained in step 2, and it is ready.

Example Embodiment

[0029] Example 2

[0030] Step 1. Weigh the following components according to mass percentages: 52% calcium carbonate, 45% calcium sulfate (green gypsum), 1% clay, 2% adsorbent, totaling 100%.

[0031] Step 2. Heat the raw gypsum to 80°C to partially dehydrate it to become mature gypsum. Then add 15% water and stir in the plaster of paris, then add calcium carbonate, clay and adsorbent, stir together into a paste, and pour it into the model It solidifies to obtain a shaped chalk.

[0032] Step 3, smear a layer of paraffin wax on the circumferential surface of the chalk obtained in step 2, and it is ready.

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Abstract

The invention discloses a preparation method of a dustless damp-proof chalk. The preparation method comprises the following steps: 1. weighing the following components in percentage by mass: 45-55% of calcium carbonate, 45-55% of plaster stone, 1-2% of clay and 2-5% adsorbent, wherein the sum of the percentages by mass is 100%; 2. heating up the plaster stone to 60-80 DEG C to partially dehydrate the plaster stone to form calcined gypsum, adding 10-15% of water into the calcined gypsum, stirring, adding 45-55% of calcium carbonate, 1-2% of clay and 2-5% adsorbent, stirring the components to form paste, filling the paste into a model, and solidifying the paste to obtain a formed chalk; and 3. coating a layer of damp-proof material on the circumferential surface of the chalk obtained in the step 2 to obtain the dustless damp-proof chalk. The chalk prepared by the method disclosed by the invention is particularly suitable for use and storage in wet areas.

Description

technical field [0001] The invention belongs to the technical field of teaching supplies, and relates to a preparation method of dust-free and moisture-proof chalk. Background technique [0002] The chalk used now mainly contains two kinds of common chalk and dust-free moisture-proof chalk, and its main component is calcium carbonate (limestone) and calcium sulfate (gypsum), or contains a small amount of calcium oxide. [0003] Writing on the blackboard with chalk is to apply gypsum powder to the blackboard. When wiping the blackboard, gypsum dust (chalk dust) floats in the air for a short time and then falls on the surface and the ground near the blackboard. Dust-free and moisture-proof chalk is an improved product of ordinary chalk, which is used to eliminate chalk dust pollution in classrooms. Generally, oils or polyalcohols are added to ordinary chalk as adsorbents, and then fillers with larger specific gravity, such as clay, marl, cement, etc., can increase the specif...

Claims

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Application Information

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IPC IPC(8): C09D13/00
Inventor 王祯怡
Owner 西安佳迅科技有限公司
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