03
2023
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01
Setting time during gypsum board production
Both gypsum board production line and gypsum line equipment use gypsum powder, but different gypsum products have different setting time due to temperature, raw materials, product thickness and other aspects. If the setting time process of gypsum board or line will directly affect its production capacity, today we will look at the setting time problem in the production process of gypsum board.
The setting time includes initial setting time and final setting time. The initial setting time is the time from the time when gypsum powder is sprinkled into water to the time when gypsum slurry loses fluidity and begins to thicken under the water consumption of standard consistency (standard consistency); The final setting time is the time from the time when gypsum powder is sprinkled into water to the time when gypsum paste is solidified under the standard consistency water consumption. According to relevant standards, the setting time of qualified gypsum powder should be: under standard consistency, the initial setting time should not be less than 7 min, and the final setting time should not be more than 30 min.
Setting time is an important technical parameter in the manufacturing of gypsum board production line. Proper setting time is the prerequisite and necessary condition for normal use of gypsum powder in production. In production, we need the setting time of gypsum powder "not too short for initial setting and not too long for final setting", or "longer for initial setting and shorter for final setting". Because the initial setting time is too short or the final setting time is too long, which will affect production. The initial setting time is too short, less than 7min, which shows that the barrel is injected during production, delaying production; If the final setting time is too long, which is much longer than 30min, the slurry is too thin and easy to run when gypsum line equipment is used, and even the gypsum slurry does not set, which also affects production. In large-scale production, combining with the actual situation and taking into account various factors such as operation, the initial setting time should be controlled at about 12 min and the final setting time should be controlled at 25~30 min. The length of setting time (initial setting and final setting) is mainly related to the ratio of gypsum powder to water (gypsum water ratio). The higher the ratio of paste to water, the shorter the setting time.
The test of setting time in production is not necessarily carried out under the water consumption of standard consistency, but should be carried out according to the ratio of paste to water in large production, which has more practical significance.
Determination method: At present, the detection methods include cutting test cake method (scratch method) and Vicat method (similar to cement industry detection). We often use the simple method of cutting and testing cake (scratch method).
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