Compositions with synthetic gypsum and methods

Patent metadata

Field	Value
Publication number	US-2016107931-A1
Application number	US-201414514961-A
Country	US
Kind code	A1
Filing date	Oct 15, 2014
Priority date	Oct 15, 2014
Publication date	Apr 21, 2016
Grant date	—

Abstract

DTPA-coated synthetic calcined gypsum is provided with alpha-like properties and obtained by spray-coating the synthetic caclined gypsum with DTPA. Cementitious compositions comprising DTPA-coated synthetic calcined gypsum and low water demand are provided as well. Methods for controlling an open time of a cementitious slurry by increasing or decreasing the amount of DTPA-coated synthetic calcined gypsum in the slurry are provided as well.

First claim

What is claimed is:

1 . Synthetic calcined gypsum coated with diethylene-triamine-pentaacetic acid (DTPA), wherein the synthetic calcined gypsum is obtained by spray-coating the synthetic calcined gypsum with DTPA in a fluidized bed chamber at a temperature in the range from 190 degrees Fahrenheit to 340 degrees Fahrenheit.

2 . The synthetic calcined gypsum coated with DTPA of claim 1 , wherein the setting time of the DTPA-coated synthetic calcined gypsum is from 150 to 300 minutes.

3 . The synthetic calcined gypsum coated with DTPA of claim 1 , wherein the temperature is in the range from 212 degrees Fahrenheit to 300 degrees Fahrenheit.

4 . The synthetic calcined gypsum coated with DTPA of claim 1 , wherein DTPA is used at 0.1 to 1.0 lbs/min for spray coating of the synthetic calcined gypsum in the fluidized bed chamber.

5 . The synthetic calcined gypsum coated with DTPA of claim 1 , wherein the DTPA-coated calcined gypsum is obtained without drying the DTPA-coated calcined gypsum after it exits from the fluidized bed chamber.

6 . The synthetic calcined gypsum coated with DTPA of claim 1 , wherein the dosage rate of spray coating with the DTPA is in the range of 0.1 to 40 lb/min of the DTPA liquid onto the synthetic calcined gypsum with a flow rate of approximately 9-11 tons/hour.

7 . The synthetic calcined gypsum coated with DTPA of claim 1 , wherein the DTPA-coated synthetic calcined gypsum is obtained by spray-coating the synthetic calcined gypsum with DTPA and additionally by spray-coating with a second compound selected from the group consisting of tartaric acid, citric acid, proteinaceous retarder, sodium citrate, cream of tartar, Rochelle salts, retard K, SUMA retarder, Climatic Stable Accelerator (CSA®), Heat Resistant Accelerator (HRA®), TERRA ALBA® gypsum accelerator, aluminum sulfate, zinc sulfate, potassium sulfate and any combination thereof.

8 . The synthetic calcined gypsum coated with DTPA of claim 7 , wherein the second compound is pre-mixed with DTPA prior to spray coating.

9 . The synthetic calcined gypsum coated with DTPA of claim 7 , wherein the DTPA-coated synthetic calcined gypsum is obtained by spray-coating the second compound on the synthetic calcined gypsum first, and by subsequently spray-coating with DTPA.

10 . A cementitious composition comprising DTPA-coated synthetic calcined gypsum and at least one natural calcined gypsum, and wherein the water demand for the composition is no more than 50 cc for 100 parts of all stucco combined.

11 . The cementitious composition of claim 10 , wherein the natural calcined gypsum is selected from the group consisting of alpha calcined gypsum, low consistency alpha calcined gypsum and beta calcined gypsum.

12 . The cementitious composition of claim 10 , wherein the natural calcined gypsum is spray coated with DTPA.

13 . The cementitious composition of claim 10 , wherein DTPA-coated synthetic calcined gypsum comprises from 0.1% to 25% of all gypsum in the composition, based on the dry weight.

14 . The cementitious composition of claim 10 , wherein the DTPA-coated synthetic gypsum comprises at least 25% of all gypsum in the composition, based on the dry weight.

15 . The cementitious composition of claim 10 , wherein the DTPA-coated synthetic gypsum comprises from 25% to 85% of all gypsum in the composition, based on the dry weight.

16 . The cementitious composition of claim 10 , wherein the composition further comprises at least one type of cement.

17 . The cementitious composition of claim 10 , wherein the cement is selected from the group consisting of white cement, raw PORTLAND type cement, imp milled cement and class C cement.

18 . The cementitious composition of claim 10 , wherein the composition further comprises a pozzalon selected from the group consisting of fly ash, slag cement and silica fume

19 . The cementitious composition of claim 17 , wherein the composition further comprises a pozzalon selected from the group consisting of fly ash, slag cement and silica fume

20 . A method of preparing a cementitious slurry with a predetermined open time, the method comprising controlling the open time of the slurry by increasing the amount of DTPA-coated synthetic calcined gypsum in the slurry from 0% to a value in the range from 0.1% to 25%, wherein increasing the amount of the DTPA-coated synthetic calcined gypsum in the slurry increases the open time.

Assignees

• United States Gypsum Co

Inventors

• Lettkeman Dennis Mark
• Wilson John Wesley
• Cloud Mike L
• Ball Brian K
• Kaligian Raymond A
• Blackburn Doug

Classifications

• Y02W30/91

  Use of waste materials as fillers for mortars or concrete · CPC title

• C04B11/00 Primary

  Calcium sulfate cements · CPC title

• C04B7/04

  using raw materials containing gypsum {, i.e. processes of the Mueller-Kuehne type} · CPC title

• C04B20/12 Primary

  Multiple coating or impregnating · CPC title

• C04B2103/0031

  Type C · CPC title