Titanium gypsum is a kind of waste residue with dihydrate gypsum as the main component, which is produced by adding lime (or calcium carbonate) to neutralize a large amount of acid wastewater in order to treat acid wastewater when titanium dioxide is produced by sulfuric acid method. The discharge of titanium gypsum not only occupies a lot of land and pollutes the environment, but also causes a great economic burden to titanium dioxide enterprises. Titanium gypsum can be used to make cement retarder after being processed by grinding machine. Guilin Hongcheng is a professional manufacturer of titanium gypsum grinding mill. The following describes how to prepare titanium gypsum composite cementitious materials with good performance.

titanium gypsum grinding mill-HC pendulum Raymond mill

1. What is the effect of adding various admixtures in titanium gypsum on its performance?

The strength property of titanium gypsum after physical modification has a certain gap with that of natural gypsum and other chemical gypsum. Some additives must be added to improve the strength property of titanium gypsum. The additives used include desulfurization ash, fly ash, water quenched slag, alum, water reducer and retarder.

When the water quenched slag is used as light aggregate, when the content is less than 40%, it will not affect the strength of the titanium gypsum product, and can effectively reduce the bulk density of the product; When the content of fly ash is less than 30%, it has a little effect on improving the strength of titanium gypsum, but when the content of fly ash is more than 30%, it will reduce the strength of titanium gypsum, and fly ash is helpful to improve the late strength of titanium gypsum (7d). Desulfurized ash can significantly improve the strength of titanium gypsum. With the increase of its content, the strength of titanium gypsum products can be significantly improved. Alum can effectively improve the strength of titanium gypsum, and when the content is 3%, the effect is the best; The amount of water added has an obvious effect on the strength of titanium gypsum. With the increase of the amount of water added, the strength of the sample decreases significantly. Therefore, while ensuring the fluidity of gypsum paste, the lower the amount of water added, the better.

As light aggregate, water quenched slag can improve the bulk density of titanium gypsum trial products. Desulfurized ash, fly ash and alum can significantly improve the strength performance of titanium gypsum. Therefore, titanium gypsum, desulfurized ash and fly ash are selected as the powder, water quenched slag is used as the light aggregate, and alum, melamine and citric acid are used as the additives. The best parameters are found by changing the proportion of the powder. The proportion of aggregate is 40% of the powder, the proportion of alum in the additive is 3% of the powder, the proportion of melamine and citric acid is 1% respectively, and the addition of titanium gypsum 70% and desulfurized ash 30%, the performance of the cementitious material is good.

2. How to prepare titanium gypsum composite cementitious material with good performance?

After calcining for 2h at 600℃, titanium gypsum is compounded with fly ash, slag and cement to shorten the initial setting time of the composite to 3h, the final setting time to 5h, and the 28d flexural strength and compressive strength reach 4.3MPa and 13.6MPa respectively. With titanium gypsum and slag as basic components, cement clinker and composite early strength water reducer can be used to prepare cement with excellent performance, and its strength and water resistance are obviously superior to that of building gypsum. The research shows that the strength of titanium gypsum mixed cementitious material after natural curing for 28 days can meet the requirements of building wall materials and municipal road subgrade mixed materials, its dissolution rate is less than 20% of building gypsum, and its water absorption rate is about 50% of building gypsum, indicating that titanium gypsum composite cementitious material has excellent water resistance. If titanium gypsum fly ash slag composite cementitious material is not mixed with activator, its setting time is long and its early strength is low. Adding proper amount of cement to this composite cementitious material can obviously shorten the setting time of the composite cementitious material, which is conducive to the growth of the strength of the composite cementitious material.

Some research results show that adding 5% cement to the titanium gypsum fly ash slag composite cementitious material can shorten the initial setting time of the composite cementitious material to 4h, the final setting time to 9h, and the 28d flexural strength and compressive strength can reach 5.8MPa and 29.OMPa respectively. High performance composite cementitious materials can be prepared by using titanium gypsum, fly ash, slag and a small amount of Portland cement or clinker, selecting appropriate activator and taking appropriate process measures. The research shows that adding 5% alunite into the titanium gypsum fly ash slag composite cementitious material can shorten the initial setting time of the composite cementitious material to 1h, the final setting time to 2h, and the 28d flexural strength and compressive strength reach 9.5 MPa and 53.0 MPa respectively, reaching the strength standard of 525R slag Portland cement.

3. How do different kinds of activators affect the strength of titanium gypsum composite cementitious materials?

The strength of composite cementitious material can be greatly improved after calcination of titanium gypsum. The 28d strength of the composite cementitious material excited by cement alone increased by 70%, and the flexural and compressive strength of the composite cementitious material increased with the increase of cement content. When the cement content is 15%, its strength is the highest. When the lime content is 15%, the cement content is 0, and its strength is the lowest. In the calcined titanium gypsum fly ash system, the use of cement excitation is more conducive to improving the strength of the system.

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