SIPERNAT® speciality silica and AEROSIL® fumed silica for the salt industry

Industry Information 2124

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Salts are among the most important raw materials. Especially sodium chloride, below referred to as “common salt” or briefl y “salt”, is widely used in food as well as in industrial applications. Today there are a many diff erent grades of salt, with diff erent particle sizes, structures and contents of trace mine rals.

• Improved fl owability • More accurate dosing of salt into mixtures

• Reduced caking tendency • Improved storage stability • Increased productivity • Constant quality • Cost savings • Reduced dustiness

In order to ensure exact dosing, it is cru-cial that the salt shows good fl owability and does not cake on storage. SIPERNAT® speciality silica and AEROSIL® fumed silica are able to help provide excellent fl ow and long lasting storage stability for your salt grades.

What can SIPERNAT® speciality silica and AEROSIL® fumed silica do for you?

Figure 1: Free-flowing salt at the breakfast table

Benefits for you and for your customer:

The mentioned benefi ts also hold true for industrial salts other than sodium chloride.

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Salts may pick up moisture from the air, resulting in the formation of saturated brine on the surface of the salt particles. For each salt there is a characteristic rela-tive humidity that leads to this eff ect. It is equal to the water activity of the saturated solution of the respective salt. For com-mon salt this is 75 % relative humidity at 20 °C. Commercial grades of com-mon salt however contain traces of more hygroscopic minerals such as magnesium chloride or calcium chloride. They liquefy

Reasons for insufficient flowability and caking

at a relative humidity of 33 % and 31 % respectively. Furthermore salt crystals can adsorb traces of water even before the critical ambient humidity is reached. Thus, when storing salt, liquid bridges may form between the crystals, the salt becomes damp and the fl owability decreases. Fur-thermore fl uctuating relative humidity or temperature during storage may lead to repeated dissolving and recrystallisation resulting in hard caking.

SIPERNAT® speciality silica and AEROSIL® fumed silica consist of very fi ne particles. They are able to cover the surface of salt crystals and act as distance holders or spacers. Moreover they have a high absorption capacity and can absorb liquid fi lms from the surface of salt particles effi ciently. The salt stays dry, fl ows well and does not cake. Even sea salt grades, containing traces of more hygroscopic minerals such as calcium or magnesium salts, can be kept dry and free fl owing with the addition of silica products.

SIPERNAT® speciality silica and AEROSIL® fumed silica help keep salt flowable and prevent caking

Figure 2: Salt crystal without and with silica

Figure 3: Flowability of sea salt without and with silica

Hexacyanoferrates are used to keep sodi-um chloride from caking however their mode of action is diff erent from the way silica works. They work by penetrating into the surface of the salt and changing the crystal structure when exposed to humidity thus reducing caking. They are not able to prevent more hygroscopic salt grades from becoming damp and sticky.

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Figure 5 shows the fl ow improvement of pure sodium chloride containing 0.6 % water, treated with diff erent types of SIPERNAT® speciality silica and AEROSIL® fumed silica and with a common grade of TCP* (Tricalcium phosphate). The tests were performed using a set of six glass funnels (fi gure 4) with diff erent outlet diameters. The evaluation is made with

Experimental data

the grades “1” = excellent fl ow behaviour, i. e. the salt fl ows out from funnel No. 1 with the smallest opening without stop-ping, to grade “7” = poor fl ow behaviour, i. e. the salt no longer fl ows even through funnel No. 6 with the largest orifi ce. As can be seen any of the SIPERNAT® spe-ciality silica and AEROSIL® fumed silica grades improved the fl ow considerably.

In order to obtain an optimum result when using a fl ow or anticaking agent, it is crucial to work with a suitable mixing equipment. Ploughshare mixers, paddle mixers, or ribbon blenders proved to be highly effi cient for this purpose. The fi lling level should not exceed 70 % of the mixer’s volume. The mixing time is dependent on the type of mixer; how-ever, usually it will amount to only a few minutes in any case.

Mixing technology

Detailed information on mixing technol-ogy is given in our Technical Information 1213 “Silica as fl ow agent and as carrier – Suitable mixing processes for powders and granulates”.

Figure 4: Set of glass funnels

* Tested product Cafos M, producer Budenheim, Germany

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The following table lists the most appli-cable grades of SIPERNAT® speciality silica and AEROSIL® fumed silica for use in common salt. Individual grades of salt may need a particular type of SIPERNAT® speciality silica and AEROSIL® fumed silica for best performance.

Recommended products

We will be happy to answer your ques-tions in detail and assist you in choos-ing the right product for your individual application as well as information for best handling and processing our products.

Table 1

AEROSIL® 200 F Fumed silica with very fine particles, high chemical purity and high absorption capacity. Especially recommended for grades of highly chemical purity.

SIPERNAT® 22 S Silica with fine particles and high absorption capacity. Recommended for highly hygroscopic salt grades such as sea salt.

SIPERNAT® 50 S Silica with fine particles and very high absorption capacity. Especially recommended for highly hygroscopic salt grades such as sea salt.

Usual silica grades of Evonik Industries AG for the use in common salt

Figure 5

7

6

5

4

3

2

1

00,0% 0,2% 0,4% 0,6% 0,8% 1,0% 1,2% 1,4% 1,6% 1,8%

SIPERNAT® 22 S SIPERNAT® 50 SAEROSIL® 200 F TCP

Addition level flow aid

Flow

gra

de

Flow improvement salt

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Evonik Industries AG – your global partner

Handling, packaging and storage

Packaging & handlingAEROSIL® and SIPERNAT® products are delivered in multiply bags of vari-ous weights, depending on the product and market. We also off er certain silica products in semi-bulk packaging – the FIBC (Flexible Intermediate Bulk Con-tainer). The FIBC option off ers dust-free discharge, requires less manual labor (compared to paper bags) and eliminates any possible risk of external contamina-tion in a closed system. Bulk deliveries are available as well. For more information on packaging, please request our Technical Information 1232 “ Types of Packag-ing for Performance Silica, the Technical Information 1231 “Packaging Forms

for AEROSIL®”, the Technical Informa-tion 1219 ”Semi-bulk Packaging for AEROSIL®“ or the Technical Information 1321 “Semi Bulk Packaging for fi ne parti-cle SIPERNAT® products”. Several options for dust free and automated handling (conveying, dosing, feeding etc.) into both solid or liquid systems are possible. For more detailed information regarding the handling of silica, please request our Technical Bulletin Fine Particles No 28 “Handling of synthetic silica and silicate”.

Please contact a sales agent in your area for detailed product / packaging / handling specifi c information.

Wesseling, Deutschland

Ta Yuan, Taiwan

Map Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, ThailandMap Ta Phut, Thailand

Gajraula, Indien

Zubillaga-Lantaron, Zubillaga-Lantaron, Zubillaga-Lantaron, Zubillaga-Lantaron, Zubillaga-Lantaron, Zubillaga-Lantaron, Zubillaga-Lantaron, SpanienSpanienSpanienChester, PA, USAChester, PA, USAChester, PA, USA Akoh, JapanAdapazari, TürkeiAdapazari, TürkeiAdapazari, TürkeiAdapazari, TürkeiAdapazari, TürkeiAdapazari, TürkeiAdapazari, TürkeiAdapazari, TürkeiAdapazari, TürkeiAdapazari, TürkeiAdapazari, Türkei

AT-Center, Shanghai, AT-Center, Shanghai, AT-Center, Shanghai, AT-Center, Shanghai, ChinaAT-Center, Shanghai, ChinaAT-Center, Shanghai,

AT-Center, Piscataway, USAAT-Center, Piscataway, USAAT-Center, Piscataway, USA

Rheinfelden, Deutschland Rheinfelden, Deutschland Rheinfelden, Deutschland Leverkusen, Deutschland Leverkusen, Deutschland Leverkusen, Deutschland

Roussillon, FrankreichRoussillon, FrankreichRoussillon, FrankreichRoussillon, FrankreichRoussillon, FrankreichRoussillon, FrankreichRoussillon, FrankreichRoussillon, FrankreichRoussillon, FrankreichRoussillon, FrankreichRoussillon, Frankreich

Antwerpen, BelgienAntwerpen, BelgienAntwerpen, BelgienAntwerpen, BelgienAntwerpen, BelgienAntwerpen, BelgienAntwerpen, Belgien

Yokkaichi, JapanYokkaichi, JapanYokkaichi, Japan

Waterford, USAWaterford, USAWaterford, USAWaterford, USAWaterford, USAWaterford, USAWaterford, USA

AT-Center, Hanau-Wolfgang, DeutschlandAT-Center, Hanau-Wolfgang, DeutschlandAT-Center, Hanau-Wolfgang, Deutschland

Mobile, USAMobile, USAMobile, USA

Production sites silica, AT-CenterJoint Venture

Nanping, ChinaNanping, ChinaNanping, China

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• Silica as a fl ow aid and carrier – suitable mixing processes for powder and granulates, Technical information TI 1213, Evonik Industries AG.

• SIPERNAT® speciality silica and AEROSIL® fumed silica in the food industry, Industry-Information II 2129, Evonik Industries AG.

Additional publications on the subject

Food additive information

• SIPERNAT® speciality silica and AEROSIL® fumed silica as fl ow aid and anticaking agent, Technical Information TI 1351.

www.sipernat.com • www.aerosil.com

All hydrophilic SIPERNAT® speciality silica and AEROSIL® fumed silica men-tioned in this brochure comply with 21 CFR (Code of Federal Regulations, USA) § 172.480. Silicon diox ide is listed as “anticaking agent” which “may be safely used at a level not exceeding 2 %”.

The mentioned hydrophilic SIPERNAT® speciality silica and the mentioned AEROSIL® fumed silica, are in line with

food additive requirements for E 551 according to EU-directive 2008 / 84 / EC, as we know from typical data. All silica products mentioned in this brochure are HACCP conform.

Kosher and Halal certifi cates are available on request.

StorageAlthough AEROSIL® and SIPERNAT® products are largely chemically inert and their composition does not change chemi-cally over time, their high specifi c surface area could result in the adsorption of vola-tile substances (in the case of moisture, this adsorption is reversible).

For this reason, we recommend storing all AEROSIL® and SIPERNAT® products in a dry place, protected from moisture

and organic vapors. For more detailed information regarding the stability of silica please request the corresponding Product Information. During prolonged periods of storage, AEROSIL® fumed silica and SIPERNAT® precipitated silica may become slightly compacted. This can lead to a minor increase in tamped density, aff ecting the related product properties.

Europe / Middle-East / Africa / Latin AmericaEvonik Resource Effi ciency GmbHBusiness Line SilicaRodenbacher Chaussee 463457 Hanau-WolfgangGermany +49 61 81 59-8118 +49 61 81 59-78118ask-si@evonik.com

www.evonik.com

North AmericaEvonik CorporationBusiness Line Silica299 Jeff erson RoadParsippany, NJ 07054-0677USA +1 800 233-8052 +1 973 929-8502ask-si-na� a@evonik.com

Asia / Pacifi cEvonik (SEA) Pte. Ltd.Business Line Silica3 International Business Park#07 – 18 Nordic European CentreSingapore 609927

+65 6 809-6877 +65 6 809-6677ask-si-asia@evonik.com

This information and any recommendations, technical or otherwise, are presented in good faith and believed to be correct as of the date prepared. Recipients of this information and recommendations must make their own determination as to its suitability for their purposes. In no event shall Evonik assume liability for damages or losses of any kind or nature that result from the use of or relianceupon this information and recommendations. EVONIK EXPRESSLY DISCLAIMS ANY REPRESENTATIONS AND WARRANTIES OFANY KIND, WHETHER EXPRESS OR IMPLIED, AS TO THE ACCURACY, COMPLETENESS, NON-INFRINGEMENT, MERCHANTABILITY AND / OR FITNESS FOR A PARTICULAR PURPOSE (EVEN IF EVONIK IS AWARE OF SUCH PURPOSE) WITH RESPECT TO ANY INFORMATION AND RECOMMENDATIONS PROVIDED. Reference to any trade names used by other companies is neithera recommendation nor an endorsement of the corresponding product, and does not imply that similar products could not be used. Evonikreserves the right to make any changes to the information and / or recommendations at any time, without prior or subsequent notice.

AEROSIL® and SIPERNAT® are registered trademarks owned by Evonik Industries AG or its subsidiaries.

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