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Our story

The Silox company was created on 22 December 1983 with the aim of producing zinc oxides from Prayon zinc hydroxides (generated through its sodium hydrosulfite process). However, the roots of Silox can be found in a rich industrial heritage of almost two centuries, dating to 30 July 1828 and the founding of the “Société Métallurgique d’Engis” (Engis Metallurgical Company). The purpose of the latter was to exploit the lead and zinc ore mines of Engis (Mallieue, Dos and Fagnes sites) and Les Awirs.

Before the creation of Silox, zinc hydroxides produced by Prayon were sold to, among others, a French company, Etablissements Silar. This company had itself been founded on 26 May 1932 in the Paris region by two entrepreneurs: the family of one is still at the helm of the company today. It was Silar who pioneered the development of active grades of zinc oxide that are so popular today in rubbers and tires. Silox was born from the association of Prayon and Silar.

Over the intervening years, Silox has diversified considerably, both by organic growth and through acquisitions. Today, the Silox group is a world leader in:

Zinc and sulphur chemical processing

Anticorrosion pigments

Recycling of metal-bearing complex residues

We are leaders in our field

Today, Silox is

  • The only manufacturer of sodium hydrosulfite-based reducing and bleaching agents, with production units on three continents and expertise in the two main production processes: the zinc dust process and the sodium formate process.
  • The leading specialist in high-performance active zinc oxides for use in rubber.
  • World leader in anticorrosive pigments.
  • World leader in sulfoxylates used as discharge agents in textile printing, as redox catalyst in polymerization process for manufacturing polymer/synthetic rubbers such as ABS, SBR, NBR, and as an antioxidant in drug formulation.
  • Internationally renowned in recycling non-ferrous metal residues with a unique positioning as both trader and value-adding refiner using hydro- and pyro-metallurgical processes.

Creation of the company Société Métallurgique d’Engis to exploit the lead and zinc ore mines of Engis and Les Awirs.


Creation of the company Société de la Nouvelle Montagne to exploit a zinc and lead mine in Verviers.


Merger of Société Métallurgique d’Engis and Société de la Nouvelle Montagne under the name of S.A. Nouvelle Montagne to operate the zinc and lead mines of Engis, Prayon and Verviers.


Nouvelle Montagne decides to develop its downstream activities and creates the Société des Produits Chimiques d’Engis with other investors with the aim, among other things, of better exploiting the sulfur contained in the zinciferous ores.


Nouvelle Montagne absorbs the Société des Produits Chimiques d’Engis.


Creation of Etablissements Silar in Paris, France for the production and sale of chemicals. Silar purchases zinc hydroxide to produce zinc oxide for rubber manufacturers.


The Société Métallurgique de Prayon takes over the S.A. Nouvelle Montagne.


Start of the production of sodium hydrosulphite in Engis based on the zinc dust process.


Creation of a new site in Ehein (Engis) to produce zinc metal by electrolysis. The company will later become Hydrometal S.A.


Prayon and Silar (later Cybelle S.A.) join forces to create the Société Industrielle Liégeoise des Oxydes (Silox) for the purpose of producing and marketing zinc oxides.


Silox takes control of the Canadian company Hydro Technologies Inc. (HTCI), which produces zinc oxide and sodium hydrosulphite-based liquid bleaching agents.


Silox acquires the French company Société Nouvelle des Couleurs Zinciques (SNCZ), a global leader in the field of anticorrosive pigments, especially zinc phosphates and strontium chromates.


Silox acquires a controlling interest in Transpek-Silox Industry Ltd., which has four plants in India and produces zinc dust and oxides, zinc and sodium sulphoxylates, as well as sodium hydrosulphite and liquid SO2.


Silox acquires Prayon’s sodium hydrosulphite- and sulphur dioxide-linked activities.
Silox acquires the Brussels-based company Jean Goldschmidt International (JGI) and, indirectly, its Ehein-based subsidiary, Hydrometal. The JGI group is specialized in marketing complex residues of non-ferrous metals as well as treating and recovering them by hydrometallurgy.


Silox signs an agreement with Clariant UK to take over its sodium hydrosulphite business. Silox UK is set up and brings Clariant UK’s Technical Service Team on board.


Silox acquires an additional 15% of its Indian subsidiary Transpek-Silox Industry Ltd’s capital, raising its holding to 83.28%.


Creation of Silox Belgium and transfer of production-related assets in Engis (sulphur dioxide, hydrosulphite and zinc oxide). Silox SA becomes a holding company.
Jean Goldschmidt International sets up Harz Oxid GmbH in Germany, a 50/50 joint venture with Zinc Nacional S.A., in order to acquire the Zinc Recycling Business of Harz-Metall GmbH.


Jean Goldschmidt International acquires the assets of Aliphos in Dunkerque, France, to set up Hydrometal France to develop innovative activities for the production of metal salts, essentially from secondary materials.


Transpek-Silox Industry Ltd. and Hydro Technologies Inc. are renamed Silox India and Silox Canada, respectively.
In collaboration with the CRM Group, Hydrometal, a subsidiary of Jean Goldschmidt International, builds a plasma oven, unique in Europe, for testing and developing new ways to recycle non-ferrous materials.

Our markets

Our products and their applications

Tyres & Rubber

Silox offers a wide range of zinc-based activators for rubber vulcanization (zinc oxides, zinc carbonate), and it was Silox who first launched active grades of zinc oxide which have strongly influenced the rubber industry.

The use of zinc in vulcanization helps improve the physical properties of rubber, such as its tensile strength, tear resistance, and elasticity. It also helps improve rubber’s resistance to heat, ozone, and UV light, making it more durable and longer-lasting. Overall, the use of zinc in vulcanization helps improve the performance and longevity of rubber products, such as tires, hoses, seals and technical rubber goods.

Silox also offers variants with very low environmental impact (ZinecoTM) and continues to innovate in this application field by developing ever more active products (ActiECO+TM), which allow a 1:1 replacement of conventional zinc oxides without any need for reformulation.

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Pulp & Paper

The paper and pulp market has evolved significantly over the years, driven by technological advances and changing consumer preferences.

One major development has been the emergence of digital technologies, which have led to a decline in the demand for traditional paper products, such as newspapers and magazines. This has led to a shift in the focus of the paper and pulp industry towards the production of specialty and technical papers. There has also been a trend towards greater efficiency and sustainability in the paper and pulp industry, with many companies implementing measures to reduce water and energy usage, minimize waste, and reduce their carbon footprint.

Silox offers a wide range of hydrosulphite-based bleaching agents in different forms (liquid solutions, customized blends, stable powders) for the paper industry, and also provides a support service allowing customers to fine-tune their consumption in order to maximize performance, avoid losses, reduce costs and limit the environmental impact of their activity. Silox works tirelessly to reduce its own emissions, thus contributing to improving the impact of the entire value chain.

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The textile industry has a long and rich history dating back to ancient civilizations. Early textiles were made by hand using simple tools and techniques, such as spinning and weaving. As civilizations developed, the textile industry underwent several major changes and innovations that greatly impacted the production and distribution of textiles.

In the 20th and 21st centuries, the textile industry has continued to evolve and adapt to changing market conditions and technological advancements. The widespread adoption of automation and computerization has led to the development of more efficient and precise production methods, and the use of synthetic fibers and new finishing techniques has resulted in the creation of a wide variety of innovative textiles.

Silox offers a large range of products for the textile industry such as:

  • Sodium hydrosulphite used in vat/indigo dyeing, reduction clearing of dyed synthetic fabrics and yarns, cleaning dye-soiled dyeing machines, and stripping fabrics before re-dyeing;
  • Sodium formaldehyde sulphoxylate (SafoliteTM) and zinc formaldehyde sulphoxylate (SafolinTM) used as a discharge printing agent on cotton and synthetic fabrics;
  • Specialized denim grade sodium hydrosulphite (Hydros DTM) and proprietary reducing agents (LeucoSAFE D7TM, BleachtsilTM, Siloxin STTM)

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Fiber recycling

Textile fiber recycling or regeneration refers to the process of recovering and reusing fibers from discarded textiles. The fibers can be recovered through a variety of methods, including mechanical, chemical, and thermal processes.

There are several benefits to recycling and regenerating textile fibers. It can help to reduce the amount of waste that is sent to landfills, conserve natural resources such as water and energy, and reduce the environmental impact of producing new textiles. Additionally, recycling and regenerating fibers can be a cost-effective way for manufacturers to obtain raw materials for their products.

Silox cooperates with several players in this field by supplying reducing agents, combining efficiency and low environmental impact.

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Paints & coatings

Silox, through its subsidiary SNCZ, is a world leader in the anticorrosive pigment sector. Our product range is among the most extensive on the market (zinc phosphates, modified zinc phosphates, zinc-free phosphates, chromates, ion-exchanged silicas and polyphosphates), tailored to fulfill the most demanding needs.

With our pigments, our customers formulate the ideal anticorrosive coatings for markets as diverse as construction, automotive, industrial infrastructures, marine, aerospace and domestic appliances. We extend the life span of durable metallic goods, thus contributing to reducing the exploitation of nonrenewable natural resources.

Silox India produces zinc dust which is also used in anticorrosive paints. When applied to metal surfaces, it forms a layer of zinc oxide, which is highly resistant to corrosion. The zinc oxide layer is created through a chemical reaction between the zinc dust and the moisture in the air, a process known as galvanic corrosion. This layer acts as a barrier between the metal surface and the environment, protecting the metal from corrosion.

In addition to its corrosion-resistant properties, zinc dust is also a good reflector of infrared radiation, making it useful for heat-reflective coatings. It is a good conductor of electricity, making it useful in electrically conductive coatings.

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Trading & recycling of nonferrous metals

Silox group, through its subsidiaries JGI and Hydrometal, is a major industrial recycler dealing with a wide range of complex non-ferrous metal-bearing residues, by-products, and secondary materials including components such as zinc, nickel, cobalt, molybdenum, germanium, tin, lead, antimony, copper, rare earths and precious metals from old or new applications like solar cells, batteries, low energy lights, wind turbines, etc.

As a key player in the circular economy and urban mining, we represent a valuable alternative to landfill and, as such, contribute significantly to the development of sustainable solutions to the depletion of natural resources. Our current technical set-up is unique in the recycling world and is based on hydro- and, when needed, pyro-metallurgy.

Our hydrometallurgical processes consume very little energy and produce very small quantities of CO2.

We are extremely active worldwide in the purchasing and selling of raw materials, by-products and products, which is building our commercial strength. We either direct the sourced materials to our Hydrometal plants to be refined or, alternatively, sell them directly to third parties all around the world.

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In addition to the market segments described above, Silox products are widely used in many other applications such as:

  • Intermediates and stabilizers in pharmaceutical drug manufacturing,
  • Supplements in human and animal nutrition,
  • Micronutrient supplements in agriculture,
  • Anti-bacterial agents in personal care,
  • Very high purity (99.999%) metals for advanced electronic applications,
  • Redox catalysts in emulsion polymerization process for manufacturing ABS, SBR, X-SBR, NBR, CR, PVC-latices, PVA, EVCL, PCE, vinyl acrylate and styrene acetate,
  • Additives for the separation of metals from leaching solutions in the mining industry,
  • Fluxing agents in the preparation of frits and enamels for ceramics and floor tiles,
  • Oxygen scavenger in oil drilling fluids,
  • Reductive bleaching agents for kaolin clay,
  • Water treatment, food bleaching (jaggery, sugar, honey and gelatin), soap manufacturing and glue manufacturing, etc.

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Our companies

Group structure

Silox UK

SILOX UK hosts the technical support team for reducing and bleaching agents and administers sales of these products in England and Northern Europe.

Silox Belgium

Located at the heart of the Prayon industrial site in Engis near Liège (Belgium), Silox Belgium produces sulfur dioxide, sodium hydrosulphite-based reducing and bleaching agents and a full range of standard and active zinc oxides recognized for their quality and performance. The sodium hydrosulfite produced by the “zinc process” is internationally appreciated for its stability, high density and lack of odor.​ Silox Belgium is also home to our specialized centers of excellence in the areas of hygiene paper and fiber regeneration on the one hand, and tires and rubber on the other.

Silox India

Silox India Private Limited operates three production sites in India. The Silvassa site (Union Territory) mainly produces zinc dust for anti-corrosion coatings and the chemical and metallurgical industries. The Ekalbara plant (Gujarat) produces derivatives of zinc (oxides, carbonates, sulphates) and sulfur (sulfur dioxide, sodium metabisulfite and sodium hydrosulfite by the formate route and by the zinc route). The Atladra plant houses the headquarters of our Indian operations, our production of zinc and sodium formaldehyde sulfoxylates, an R&D center dedicated to sulfur and zinc chemistry as well as a center of excellence for textile applications. Wesbite

Silox Specialities

Silox Specialties India Private Limited is developing an innovative process for recycling battery components (lithium, cobalt, nickel) by hydrometallurgy. The process is already operating on a pilot scale and the company is looking for a new site to house a future industrial unit. The company is also counting on this new site for new developments.

Silox Can

Silox Can is a holding company that owns Silox’s interests in Silox Canada.

Silox Canada

Since its creation in 1996, SILOX Canada inc. (formerly Hydro Technologies Canada Inc.) has carved out a place for itself in the hydrosulphite and zinc oxide industry in North America for the performance of its products and for the exceptional quality of the technical support provided by our center of excellence in graphic paper. Wesbite

SNCZ France

Founded in 1984, Société Nouvelle des Couleurs Zinciques, SNCZ, is a leader in the development, production and marketing of anti-corrosion pigments. SNCZ pigments are intended to be incorporated into all types of anti-corrosion coating for the protection of metals. Its production site is located in Bouchain, in the North of France near the main North Sea ports and its products (phosphates, chromates, silicas and polyphosphates) are sold in more than 70 countries. Website

JGI Belgium

Headquartered in Brussels (Belgium) since 1960, Jean Goldschmidt International is active in the trading of complex materials containing non-ferrous metals which are difficult to process and recycle. Most of the raw materials JGI purchases, recycles and sells are qualified as wastes under international movement regulations. Moving these materials from one country to another requires full compliance with all the regulations. In addition to its international network and strong partnerships around the world, JGI’s core expertise lies in its ability to deal with the administration processes linked to the heavily regulated transport of hazardous materials (waste legislations, notifications, transportation documents, letters of credit). With offices in India, China and Thailand, JGI buys and sells materials in more than 50 countries in Europe, Asia, North and South America. Website

Hydrometal France

The Hydrometal France industrial site in Dunkirk was acquired by JGI in 2021. The group intends to develop innovative activities there to produce metal salts, including those of zinc, by hydrometallurgical means.

Hydrometal Belgium

Based in Ehein near Liège (Belgium) since 1985, Hydrometal is the industrial arm of JGI. Its expertise is based on a wide range of unique hydrometallurgical technologies for the treatment of complex residues containing non-ferrous metals often considered as toxic and hazardous waste. The industrial site is made up of 9 different factory units that can process a wide range of different materials, as well as an R&D center dedicated to hydrometallurgy. Hydrometal is particularly proud to be able to give a second life to many metals and thus contribute to extending their life cycle. Website

JGI Thailand

Since 2021, JGI Thailand has been operating a pyrometallurgical refining plant in Bangkok for secondary metallic materials, mainly tin-lead-antimony. This innovative process makes it possible to achieve very high level of purity.

Harzoxid Germany

In 2020, JGI has acquired, together with Zinc Nacional (Mexico), the zinc recycling business of Harz Metall GmbH. The site located next to the historical town of Goslar in Lower Saxony (Germany) produces Waelz oxides. ​The Waelz process is a method of recovering zinc and other relatively low boiling point metals from metallurgical waste (typically Electric Arc Furnace flue dust) using a rotary kiln. The waelz process is considered to be a “best available technology” for flue dust zinc recovery.​ The zinc enriched product referred to as Waelz oxide is a feed product for zinc smelters. Website