Sugar industry: chemical exposure in sugar production
Following a crisis period between 2017 and 2020 due to a change in regulations, the European sugar market is currently experiencing significant growth of almost 50%. As a result, both the production and consumption of sugar are increasing. Sugar is a foodstuff used by individuals as well as by industries for production purposes. The latter represent a large part of the sugar industry’s customer portfolio.
There are various types of sugar which are extracted from different plants or fruits, including white sugar, whole cane sugar and coconut sugar. The most widely consumed and known sugar, white sugar, can be extracted from two plants:
- Sugar cane, found in tropical and subtropical areas
- Sugar beet, found in various countries including France
Both plants have an identical production process except for the first stage. Sugar production from beet and cane is seasonal, with the exception of a few countries for cane sugar production.
Indeed, the harvesting of cane sugar depends on the farming practices of each country. However, its seasonal nature is a primary factor and requires a certain amount of organisation. In particular, the harvesting and production of sugar from beet takes a five-month period, from September to January. During these months, the entire sugar industry is mobilised for a very fast production pace during which machines run 24 hours a day, 7 days a week. Then, at the end of the campaign, the sugar factory switches to a different pace where the upkeep and maintenance of the industrial tools takes priority.
Despite the success of sugar companies, the seasonal aspect of the sugar industry causes various problems, particularly those related to recruitment and training. In fact, all staff dedicated to production are technicians who originally trained in other trades. They are hired on the basis of their preferred trade (electrician, mechanic, welder, etc.) and then trained as sugar workers.
As a result, there is a need for constant refresher training or renewed learning processes, especially in chemical safety. Considering the external professional commitments that some operators have, the recruitment rate is quite high.
Indeed, these workers are exposed to different types of risks throughout the manufacturing process and during site maintenance. It is therefore important to be very careful when using dangerous and noisy machines that need to be configured at very high temperatures. The use of high-temperature machinery can lead to the risk of thermal burns or respiratory problems. In addition, the use of chemicals is necessary during the manufacturing process and the handling of chemicals can lead to an
accident causing chemical injuries.
In order to better understand the chemical risks behind the manufacturing process, the different steps are presented below.
1. MANUFACTURING STEPS
1.1. Sugar cane and beet harvesting
The beet harvest takes place at the end of the year, usually between September and January. The cane harvest differs from country to country. However, harvesting and production both take place during the dry period until the beginning of the rainy season. The season can last from 4 to 11 months.
Because of the loss of sugar concentration, it is not possible to store the harvested plants. Therefore, as soon as they arrive at the factory, they are quickly washed and cut up.
1.2. Extraction and purification
Sugar extraction takes two forms:
- Diffusion for beets
- Crushing for the canes (the pieces of cane are pressed by several mills)
During this second stage, refinery operators face real chemical risks from the use of certain substances. For example, the extraction of beets requires that they be immersed in water which is gradually enriched with sugar to form a sugarcane juice. This juice contains impurities (mineral salts, organic compounds, etc.) that must be removed.
This elimination stage is called the “carbon dioxide purification” process. It consists of adding milk of lime in order to precipitate the maximum amount of non-sugars. The lime used in the milk of lime is produced on site from limestone. The carbon dioxide generated during this operation is recovered for subsequent carbonisation. The slaked lime obtained is mixed with a small amount of sugarcane juice to obtain milk of lime, which is capable of reacting with the impurities. Note that milk of lime is a saturated solution of calcium hydroxide, Ca (OH)₂. It is a corrosive substance which can cause chemical injuries if it comes into contact with skin or the eyes.
After the impurities have been removed, the carbon dioxide recovered during the previous stage or phosphoric acid is added to help remove excess lime. Carbon dioxide (CO2) is a colourless, odourless gas with a pungent taste that can cause respiratory problems and even loss of consciousness. Phosphoric acid (H3PO) is a corrosive substance which, if it comes into contact with the skin or eyes or is inhaled, can cause chemical damage to the skin, eyes or respiratory and digestive mucous membranes.
To avoid bacterial infection during the purification process, a very small amount of formaldehyde, commonly known as methanol, is required. Formaldehyde is a dangerous chemical substance due to its harmful, carcinogenic and corrosive nature. It can cause skin allergies in the event of contact. This usually manifests in the form of eczema or hives. It can also cause respiratory allergies such as asthma or allergic rhinitis.
1.3. Evaporation and crystallisation (sugar refining)
Following the carbon-calcium purification process, at this stage the filtered juice still contains 85% water, which will be eliminated by evaporation. Once boiled, it will go through several boilers at high temperatures. At the end of the cycle, a syrup composed of 70% sucrose is obtained.
This syrup is discoloured by sulphiting with sodium bisulphite or sulphur dioxide. The former is a food additive, and the latter is a colourless, dense and toxic gas which is very irritating when inhaled and results in inflammation of the respiratory system.
In a vacuum pan, very fine sugar crystals are then used to feed the syrup and its crystallisation grows. There is also a second, more popular method of refining which requires the use of chemicals such as isopropyl alcohol or anthraquinone blue. This is an eye irritant and slightly irritating to the skin. Exposure to the vapours from this product can cause eye and upper respiratory tract irritation. Anthraquinone blue does not present any particular risk.
Finally, for bleaching, refineries use sodium sulphoxylate. This is a bleaching agent that is harmful because of its ability to induce genetic abnormalities in case of exposure. Thus,care and a precise protocol of use are required to avoid any type of contamination.
1.4. Spinning, drying and conditioning
At this stage, the beet sugar mixture is sent to turbines where, through the action of centrifugal force, the white sugar is deposited on the walls. Once dried in hot air, it is cooled and stored before being packaged.
In the case of cane sugar, it will undergo three cycles of firing and spinning with the aim of extracting as much sugar as possible from the same quantity of cane. Nevertheless, the sugar recovered after each cycle will be increasingly rich in impurities. After this, the sugar is stored in different forms, either directly as a powder or in lumps after moistening and moulding. Finally, the product is shipped in bulk, by truck or rail.
2. CARE AND MAINTENANCE
Sugar production can generate dust particles that are hazardous to health. In addition to equipment, businesses have installed dust removal stations or vacuum systems.
During production periods, it is important to maintain the cleanliness that has been maintained during non-production periods. As a result, refinery cleanings are carried out on an as-needed basis at scheduled times in the production cycle. Note that sugar production is carried out on every day of the week; as a result, external cleaning teams are usually called in during these periods to ensure hygienic conditions.
These teams face different types of risks when handling corrosive or irritating chemicals. In particular, the use of sodium hypochlorite, a disinfecting agent, can cause serious skin or eye damage on contact. Caustic soda is also a powerful cleaning agent for grease removal. It is a corrosive substance that can cause serious eye and skin burns on contact. In the event of repeated or prolonged skin contact at low concentrations, inflammation of the skin layers, called dermatitis, may develop.
Finally, hydrogen peroxide is a popular industrial disinfectant. It is an irritant and can cause severe eye damage or skin irritation.
During refinery maintenance operations, pipes and drains are primarily maintained with corrosive and toxic products such as hydrofluoric acid. Hydrofluoric acid is one of the most dangeroussubstances due to its dual hazards: it is both corrosive and toxic. It causes deep burns to the skin and eyes, as well as irritation of the respiratory tract, sometimes leading to fatal poisoning.
These drains or hoses are sometimes not completely flushed, such that sprays or splashes can easily occur. These will cause serious injury even at low concentrations.
3. PREVENTION AND DECONTAMINATION METHODS
In response to this frequent use of chemicals and the risks they entail, Prevor provides decontamination solutions to prevent an injury from developing.
When using chemicals such as caustic acid, sodium sulphoxylate or even phosphoric acid, Prevor offers DIPHOTERINE® solution. It is an active and versatile washing solution for corrosive or irritating chemical splashes to the eye or skin. It is hypertonic and chemically active thanks to the DIPHOTERINE® molecule which is both amphoteric and a chelating agent. This allows the chemical to be removed from the surface of the eye or skin. In addition, it prevents penetration and ultimately extracts the chemical from the tissue if it has not yet reacted.
For hydrofluoric acid splashes, HEXAFLUORINE® is a washing solution specially designed for this type of dual-hazard product. It works in the same way as DIPHOTERINE® but acts on hydrofluoric acid and fluorides in an acidic medium. HEXAFLUORINE® solution enables the immediate extraction of the hydrofluoric acid that has penetrated and provides a greater range of intervention when dealing with a product that can be lethal.
In the case of delayed washing, i.e. washing beyond 60 seconds, both DIPHOTERINE® solution and HEXAFLUORINE® solution remain effective. Both prevent the lesion from developing further and thus reduce the damage caused.
White sugar production is seasonal and therefore requires special attention to all types of accident risk, whether thermal or chemical. In the case of chemical accidents, the handling of chemicals during production, maintenance or simple servicing plays a significant role in the risk of developing serious injuries. It is important to be equipped with personal protective equipment and an effective