METHOD FOR PRODUCING A SLOW-RELEASE SET-RETARDING AGENT FOR CEMENTING A BOREHOLE Russian patent published in 2022 - IPC C09K8/467 C04B22/06 C04B24/06 C04B103/22 B82B1/00 B82B3/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a method for producing a slow-release set-retarding agent for grouting cement. At the first stage of the method, 1 to 5 parts NH₃·H₂O and 1 to 3 parts anhydrous Na₂CO₃ are weighed and added to 100–400 ml of deionised water; mixed under room temperature, resulting in solution A; 3 to 9 parts Mg(NO₃)₂·6H₂O and 1 to 3 parts Al(NO₃)₃·9H₂O are weighed and added to 100–400 ml of deionised water; mixed under room temperature, resulting in solution B; after solution B is added to solution A, a reaction is ensured at 70 to 90°C for 7 to 9 hours; filtered using a vacuum pump and washed three times until a neutral pH level; then lyophilised at -50°C for 48 hours using a freeze dryer, resulting in a magnesium and aluminium hydrotalcite precursor. At the second stage, 1 to 3 parts magnesium and aluminium hydrotalcite precursor are weighed and dissolved in 100 to 300 ml ethylene glycol; mixed under room temperature, resulting in solution C; then 1 to 12 parts gluconic acid are weighed and added to solution C; the pH of the solution is adjusted to 4–5 while stirring, resulting in solution D. At the third stage, solution D is poured into a three-neck flask; under a temperature of 120 to 150°C, subjected to an ion exchange reaction for 2 to 5 hours, and after cooling using a vacuum pump, filtered and washed three times until a neutral pH level; then lyophilised at -50°C for 48 hours using a freeze dryer, resulting in a slow-release set-retarding agent for grouting cement; wherein the resulting slow-release set-retarding agent for grouting cement constitutes a hydrotalcite with gluconic acid inclusions of a supramolecular structure, the distance between the layers in the hydrotalcite with gluconic acid inclusions is 1.25 nm, and the height between the layers after the inclusion of gluconic acid in the hydrotalcite is 0.83 nm. Said substances herein are taken in parts by weight.

EFFECT: possibility of controlling the setting time, increase in the heat resistance of the set-retarding agent.

1 cl, 4 tbl, 4 ex