Preparation of magnesium hydroxide from leachate of dolomitic phosphate ore with dilute waste acid from titanium dioxide production

In view of the current situation where the acid resources and valuable components in titanium dioxide waste acid cannot be effectively extracted and are prone to secondary pollution, the research team proposed a new technology of step extraction and comprehensive utilization of titanium dioxide waste acid. In this paper, the preparation of doped iron phosphate from waste acid by selective precipitation was studied. The thermodynamics of selective precipitation, the effect of the reaction temperature, the initial pH value, the molar ratio of P/Fe, and the dispersant on the precipitation process were investigated in detail. The thermodynamics results show that iron(II) in titanium dioxide waste acid is oxidized and is preferentially precipitated with phosphoric acid to form iron(III) phosphate, when compared with other impurity ions. The experimental results show that the optimal precipitation condition is a temperature of 60 °C, an initial pH value of 2.5, an optimal P/Fe molar ratio of 1.1, and a dispersant polyethylene glycol at 5 mL (Per 50 mL of waster acid). After calcination, the precipitate mainly consists of iron phosphate and a small amount of aluminum phosphate. Meanwhile, the utilization ratios of iron and phosphorus were 98.81% and 98.39%, respectively. Moreover, the mass percentage of Fe2O3 and P2O5 and the molar ratio of Fe/P were 99.13% and 1.03, which basically met the requirements of the iron phosphate precursor.

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Experimental study on preparation of titanium-rich material by pressure leaching of titanium concentrate from titanium dioxide waste acid

Ferroelectrics ◽

10.1080/00150193.2021.1903258 ◽

2021 ◽

Vol 581 (1) ◽

pp. 281-286

Author(s):

Guangqiang Ma ◽

Min Cheng

Keyword(s):

Experimental Study ◽

Titanium Dioxide ◽

Pressure Leaching ◽

Rich Material ◽

Waste Acid

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Studies on the mechanism of printing film-coated tablets containing titanium dioxide in the film by using UV laser irradiation

Drug Development and Industrial Pharmacy ◽

10.1080/03639040903213725 ◽

2009 ◽

Vol 00 (00) ◽

pp. 090915102728058-8

Author(s):

Yoshiteru Kato ◽

Yasuhiko Nakashima ◽

Naoki Shino ◽

Koichi Sasaki ◽

Akihiro Hosokawa ◽

...

Keyword(s):

Titanium Dioxide ◽

Laser Irradiation ◽

Uv Laser

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Environmental benefits of magnesium hydroxide-based peroxide bleaching of mechanical pulp – mill results

TAPPI Journal ◽

10.32964/tj12.6.9 ◽

2013 ◽

Vol 12 (6) ◽

pp. 9-15 ◽

Cited By ~ 1

Author(s):

TOMI HIETANEN ◽

JUHA TAMPER ◽

KAJ BACKFOLK

Keyword(s):

Sodium Hydroxide ◽

Magnesium Hydroxide ◽

Oxygen Demand ◽

Pulp Mill ◽

Transition Metal Ions ◽

Environmental Benefits ◽

Raw Material ◽

Paper Machine ◽

High Brightness ◽

Peroxide Bleaching

The use of a new, technical, high-purity magnesium hydroxide-based peroxide bleaching additive was evaluated in full mill-scale trial runs on two target brightness levels. Trial runs were conducted at a Finnish paper mill using Norwegian spruce (Picea abies) as the raw material in a conventional pressurized groundwood process, which includes a high-consistency peroxide bleaching stage. On high brightness grades, the use of sodium-based additives cause high environmental load from the peroxide bleaching stage. One proposed solution to this is to replace all or part of the sodium hydroxide with a weaker alkali, such as magnesium hydroxide. The replacement of traditional bleaching additives was carried out stepwise, ranging from 0% to 100%. Sodium silicate was dosed in proportion to sodium hydroxide, but with a minimum dose of 0.5% by weight on dry pulp. The environmental effluent load from bleaching of both low and high brightness pulps was significantly reduced. We observed a 35% to 48% reduction in total organic carbon (TOC), 37% to 40% reduction in chemical oxygen demand (COD), and 34% to 60% reduction in biological oxygen demand (BOD7) in the bleaching effluent. At the same time, the target brightness was attained with all replacement ratios. No interference from transition metal ions in the process was observed. The paper quality and paper machine runnability remained good during the trial. These benefits, in addition to the possibility of increasing production capacity, encourage the implementation of the magnesium hydroxide-based bleaching concept.

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Development and production experience of the multilayer curtain-coated linerboard of Ji’an PM No. 3,

TAPPI Journal ◽

10.32964/tj13.2.17 ◽

2014 ◽

Vol 13 (2) ◽

pp. 17-25

Author(s):

JUNMING SHU ◽

ARTHAS YANG ◽

PEKKA SALMINEN ◽

HENRI VAITTINEN

Keyword(s):

Titanium Dioxide ◽

High Speed ◽

Food Packaging ◽

Production Efficiency ◽

Positive Impact ◽

Low Cost ◽

Board Structure ◽

Flexographic Printing ◽

Curtain Coating ◽

Coating Formulations

The Ji’an PM No. 3 is the first linerboard machine in China to use multilayer curtain coating technology. Since successful startup at the end of 2011, further development has been carried out to optimize running conditions, coating formulations, and the base paper to provide a product with satisfactory quality and lower cost to manufacture. The key challenges include designing the base board structure for the desired mechanical strength, designing the surface properties for subsequent coating operations, optimizing the high-speed running of the curtain coater to enhance production efficiency, minimizing the amount of titanium dioxide in the coating color, and balancing the coated board properties to make them suitable for both offset and flexographic printing. The pilot and mill scale results show that curtain coating has a major positive impact on brightness, while smoothness is improved mainly by the blade coating and calendering conditions. Optimization of base board properties and the blade + curtain + blade concept has resulted in the successful use of 100% recycled fiber to produce base board. The optical, mechanical, and printability properties of the final coated board meet market requirements for both offset and flexographic printing. Machine runnability is excellent at the current speed of 1000 m/min, and titanium dioxide has been eliminated in the coating formulations without affecting the coating coverage. A significant improvement in the total cost of coated white liner production has been achieved, compared to the conventional concept of using virgin fiber in the top ply. Future development will focus on combining low cost with further quality improvements to make linerboard suitable for a wider range of end-use applications, including frozen-food packaging and folding boxboard.

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