An analysis of the influence of grinding aids on the breakage process of calcite in media mills

doi:10.1163/156855299X00316

Advanced Powder Technology

Volume 10, Issue 3, 1999, Pages 223-243

https://doi.org/10.1163/156855299X00316 Get rights and content

Abstract

The effectiveness of calcium stearate, boric acid, and silica as additives for the fine grinding of calcite in media mills, i.e. ball, rod, and vibration mills, were explored, by following the size distribution of the ground product collected at various time intervals from 15 s of grinding up to 30 min, using a single size feed. While calcium stearate could achieve a modified grinding rate factor of 1.5 in the ball mill and had indicated an optimum concentration for maximum performance, both boric acid and silica remained inert materials without indicating any influence. It was also found that the presence of calcium stearate during the initial stages of grinding introduced a retardation effect on the grinding process, with the product being coarser in comparison with the blank sample. To overcome this retardation effect for the breakage process induced by the additive, it was found preferable to delay the introduction of the additive by around 5 min. Analysis of the breakage process was carried out by estimating the breakage parameters using the G-H solution for the size-discretized batch grinding equation. It was found that while the additive reduced the breakage rates of coarser size fractions during the retardation period, it helped to significantly increase the breakage rates of finer particles during the finer stages of grinding. The higher breakage rates at finer stages of grinding and the reduced agglomeration observed during this period indicate the acceptability of the alterations in the flow behavior of the mill charge as the possible mechanism for the additive in media milling.

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Grinding aids for dry fine grinding processes – Part I: Mechanism of action and lab-scale grinding
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Citation Excerpt :
This result clearly shows that the grinding aid efficiency is indeed a function of the stressing conditions provided by the mill. Similar to that, Nair and Paramasivam [80] found that the extent of enhancement within the grinding performance to grind calcite with calcium stearate as an additive varies for different media mill types. Hoffmann and Bernhardt [81] showed that different carboxylic acids do not only improve the batch-wise high pressure grinding of limestone in a vertical rolling ball mill, but also reduce the power draw of the mill drive.
Grinding aid additives are established in various industrial dry fine grinding processes, primarily to achieve either a) an increase of the production capacity, b) a decrease of the specific energy consumption or c) finer particles or a better product performance. However, even though numerous related scientific papers have already been published and a variety of grinding aids are currently applied in industrial processes, a comprehensive understanding of grinding aids is still missing. Thus, their selection and application is still mainly based on empirical knowledge. Therefore, this review gives a wide-ranging overview on grinding aids with special regard on their mechanisms of action, their impacts on the powder properties and the additive effects during lab-scale grinding. It is shown that the variety of applied substances, ground materials, target finenesses and analysis methods complicate the development of a comprehensive understanding, and how the mill type and grinding conditions influence the additive effects.
Breakage process of mineral processing comminution machines – An approach to liberation
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Energy applied methods include microwave exposure, thermal breakage, thermal shock, high-voltage pulse breakage, and ultrasonic breakage [108]. Moreover, it was shown that reagent addition before comminution can reduce particle strength [2,106,107]. One of the main purposes of breakage in mineral comminution is to liberate the mineral phases from each other.
Mineral liberation and size reduction are the most critical steps before mineral separation. Several investigations showed that mineral liberation degree could be affected by ore texture and/or loading mechanisms. However, varied definitions have been used for the breakage fundamentals as the leading cause of mineral liberation. This review identifies the breakage fundamentals and analyzes them in terms of process and ore breakage behavior. It is highlighted that the breakage fundamentals are essential for optimizing of comminution environments and designing the comminution machines. Three main areas of breakage processes in regard to fundamentals of breakage are classified and addressed as “Loading mechanism”, “Breakage mechanism”, and “Breakage mode”. Despite the fact that many advances have been made in the design of the comminution machines; still, the combined effect of breakage fundamentals and ore properties such as ore texture in a quantitative manner is not fully understood. In this regard, this study identifies and discusses the material and process factors influencing the breakage phenomenon. This potentially paves the way for improving the comminution environment concerning a particular ore type.
A critical review on the mechanisms of chemical additives used in grinding and their effects on the downstream processes
2020, Journal of Materials Research and Technology
Citation Excerpt :
GAs have been applied to address the problem of over-grinding and under-grinding (selective grinding) associated with poly-metallic sulphide ores due to their effect on producing a narrow particle side distribution [16,17]. Several investigations reported the improved material fluidity which allowed grinding at high solid concentrations (reducing the amount of processing water) [17–20]. Yusupov and Kirillova [21] reported that using GAs decreased amount of slime in the flotation feed compared to grinding without GA which is beneficial to froth flotation performance [22].
Grinding aids (GAs) have been an important advent in the comminution circuits. Over the last few decades, in order to address the high energy consumption and scarcity of potable water for mineral processing, chemical additives have become a promising alternative. Using GAs can have some advantages such as enhancing grinding efficiency, reducing water usage, improving material flowability, and narrowing the particle size distribution of the grinding products. A study on the effect of GAs on size reduction units is crucial for the beneficiation value chain of minerals and the impact on downstream processes. However, our understanding of the effects of these materials on the particle size reduction is quite limited. This article analyses the literature, which used GAs and provides a comprehensive review of their applications in the ore beneficiation processes. The outcomes of this investigation indicated that the current understanding on the mechanism of GA effects focuses only on their impacts on the product fineness and size distribution, and neglecting the aspect of energy expended and physicochemical environment. The application of GAs is mainly for rationalisation of energy where the type of reagent, pH, and ionic strength of the grinding environment is important. Gaps in knowledge of GAs are discussed in the context of addressing their use in the mineral industry, considering the mechanism of their effect, effect on grinding efficiency, and effect on the downstream processes. Addressing these gaps will pave the way for the application of GAs in improving size reduction efficiencies, which ultimately reduces environmental impacts.
Investigation on the potential of waste cooking oil as a grinding aid in Portland cement
2016, Journal of Environmental Management
Although there are several methods for managing waste cooking oil (WCO), a significant result has not been achieved in China. A new method is required for safe WCO management that minimizes the environmental threat. In this context, this work was developed in which cement clinker and gypsum were interground with various WCOs, and their properties, such as grindability, water-cement ratio required to achieve a normal consistency, setting times, compressive strength, contents of calcium hydroxide and ettringite in the hardened paste, microstructure and economic and environmental considerations, were addressed in detail. The results show that, overall, WCO favorably improves cement grinding. WCO prolonged the cement setting times and resulted in longer setting times. Additionally, more remarkable effects were found in cements in which WCO contained more unsaturated fatty acid. WCOs increased the cement strength. However, this enhancement was rated with respect to the WCO contents and components. WCOs decreased the CH and AFt contents in the cement hardened paste. Even the AFt content at later ages was reduced when WCO was used. WCO also densify microstructure of the hardened cement paste. It is economically and environmentally feasible to use WCOs as grinding aids in the cement grinding process. These results contribute to the application of WCOs as grinding aids and to the safe management of WCO.
Sustainable resource opportunity for cane molasses: Use of cane molasses as a grinding aid in the production of Portland cement
2015, Journal of Cleaner Production
Citation Excerpt :
About 2% of the Chinese electricity power was consumed and 0.7 billion tons of carbon dioxide (CO2) was emitted only in the process of clinker grinding in 2012. It was reported that cement grinding aids improve the clinker grinding process (Jankovic et al., 2004; Sohoni et al., 1991), accelerate clinker crushing, eliminate agglomeration and decrease clinker specific surface energy (Teoreanu and Guslicov, 1999; Rajendran Nair and Paramasivam, 1999). Hence, they have always applied to improve grinding efficiency and decrease the energy consumption.
Current methods used in China have failed to recycle cane molasses in an environmentally friendly way. Meanwhile, it is an urgent concern to find a cheap alternative to the present Portland cement grinding aids. However, the available literature has several limitations in properly evaluating the feasibility of using cane molasses as a Portland cement grinding aid. Therefore, the mixture of calcium sulfate and cement clinker is interground along with it, and mixture properties such as grindability, setting time, compressive strength, water absorption, compatibility with water reducing admixture, and hydration characteristics are systematically discussed and the mechanisms of these property variations are clarified. Besides, the economic, logistical, and environmental viability are also considered. The results show that cane molasses affects the cement grindability, setting time, compressive strength, water absorption, compatibility, hydration characteristics and microstructure, and these effects are related to its content. Moderate cane molasses delays the cement setting, but it is beneficial to the improvements of compressive strength, compatibility and microstructure. However, in addition to the fact that compressive strength is lowered, compatibility becomes poor, the later hydration is postponed and the microstructure gets loose, the scale of setting delay is also lessened when excessive cane molasses is used. The results also indicate it is logistically and economically feasible, also environmentally friendly that it is recycled as a cement grinding aid. These results are crucial to its sustainable and effective uses as well as the reuse of the waste containing similar matters. Additionally, this study also helps realize the sustainable production of cement, and also to contribute to the efforts at sustainable construction.
Influence of Grinding Aids on the Performance of Portland Cement
2022, Shenyang Jianzhu Daxue Xuebao (Ziran Kexue Ban)/Journal of Shenyang Jianzhu University (Natural Science)

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Advanced Powder Technology

Abstract

References (10)

Effect of fatty acid additives on the material flow properties of dry grinding

Powder Technol.

An improved method for estimating the feed-size breakage distribution functions

Powder Technol.

A G-H scheme for back calculation of breakage rate functions from batch grinding data

Powder Technol.

Grinding aids

KONA

Experiments on cement clinker grinding with additives

Dechema Monogr.

Cited by (10)

Grinding aids for dry fine grinding processes – Part I: Mechanism of action and lab-scale grinding

Breakage process of mineral processing comminution machines – An approach to liberation

A critical review on the mechanisms of chemical additives used in grinding and their effects on the downstream processes

Investigation on the potential of waste cooking oil as a grinding aid in Portland cement

Sustainable resource opportunity for cane molasses: Use of cane molasses as a grinding aid in the production of Portland cement

Influence of Grinding Aids on the Performance of Portland Cement

Original paperAn analysis of the influence of grinding aids on the breakage process of calcite in media mills

Abstract

Powder Technol.

Powder Technol.

Powder Technol.

Grinding aids

KONA

Experiments on cement clinker grinding with additives

Dechema Monogr.

Original paper
An analysis of the influence of grinding aids on the breakage process of calcite in media mills