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Influences of magnesium ions in water on gelatinization characteristics of starch and its flocculation behaviors on particles

Tang Min, Niu Xiaoying, Wen Shuming

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 1

art. no. 178149

EN

It is inevitable for the occurrence or built-ups of disturbing cations, especially Ca2+ or Mg2+ ions, in process water during the flotation of iron oxides by using starch as flocculants. In addition to alkali concentrations and temperature, water quality could have an essential role in changing the physicochemical properties of the starch solution and consequently disturbing its flocculation performance on particles. This study aims to identify the effects of magnesium ions on the gelatinization characteristics of starch and its flocculation properties on particles through a series of tests, such as flotation tests, settling tests, size analyses, zeta potentials, powder contact angle, Fourier Transform Infra-Red (FTIR) and X-ray Photoelectron Spectroscopy (XPS) measurement. All results show that magnesium ions at ≤ 4 mmol/L have a positive role due to enlarging the sizes of the particle flocs and accelerating their settling rates. The occurrence of Mg2+ ions at higher concentrations during starch gelatinization only obtains a starch sol-gel with entangled configurations and preoccupied active sites, resulting in the slower settling rate of the particle flocs and less hydrophilicity on mineral surfaces. It could be attributed to the cross-link interactions of magnesium-based precipitates with the acidic groups, especially carboxyl groups on the starch remnants. The suitable acid/base interactions between Mg(OH)2/MgCO3 compounds with these groups in the starch suspension could be beneficial for enhancing the flocculation of hematite as they could build bridges among the pieces and enlarge their sizes as a “load carrier” for aggregation with minerals. However, too much cross-linking could reentangle the remnants, block their adsorption sites on mineral surfaces, and eventually, weaken the flocculation capacity of starch.

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The effect of lizardite on talc flotation using carboxymethyl cellulose as a depressant

Deng Jie, Yang Siyuan, Zhang Wencai, Liu Cheng, Li Hongqiang

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 4

702--709

EN

The effect of lizardite on talc flotation when using carboxymethyl cellulose (CMC) as a depressant was studied by micro-flotation experiments and adsorption measurements, zeta-potential measurements, magnesium ion dissolution analysis, and solution chemistry calculation. The results for the micro-flotation experiments showed that the addition of lizardite further decreased the floatability of talc at pH 8.5 when using CMC as the depressant. The mechanism was that magnesium ions dissolved from lizardite lattice, then formed hydrolyzed species of magnesium cations and interacted with talc surfaces, which promoted CMC adsorption, and thus decreasing talc floatability.

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Ciężkie zaczyny cementowo- lateksowe odporne na działanie solanek magnezowych o różnej mineralizacji

Kątna Z.

Cement Wapno Beton

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2008

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R. 13/75, nr 4

196-204

PL

Przedstawiono wyniki badań stwardniałych zaczynów cementowych sporządzonych z ciężkich zawiesin cementowo-lateksowych, w których jako materiał wiążący zastosowano cement hutniczy CEM III/A 32,5 oraz mieszaniny cementów hutniczego i wiertniczego typu WG i G. Próbki stwardniałych zaczynów cementowych przez okres 28 dni poddawano działaniu wód złożowych z dużą zawartością jonów magnezu. Opracowano składy zawiesin cementowych dających stwardniałe zaczyny o znikomej przepuszczalności dla gazów oraz o dużej wytrzymałości na ściskanie, odporne na działanie solanek o dużej zawartości związków magnezowych.

EN

Hardened heavy-weight cement grouts with latex addition, based on the metallurgical cement CEM Ill/A 32,5 and oil well cement type WG and G were examined. The samples were stored at temperature 95°C in the magnesium-rich deposit waters and laboratory made brine. Cement grouts produced from 50% metallurgical cement CEM Ill/A and 50% oil well cement, cured in magnesium brines of lower concentration <20 Mg2+ ions/I at temperature 95°C, reveal high compressive strength. These grouts can be applied as resistant, low-permeable pipe sealing agent in oil wells cementing.