How to Choose the Best Bleaching Earth and Filter Aid Supplier, Manufacturer, Exporter and Trader

Supplier, manufacturer, exporter or trader: who are you buying from?

Clay products come from mines and processing plants, and the real quality is decided there: the deposit, the acid activation and the drying and milling. Some companies own the plant, some buy from several plants and sell on, and some only export. Each can be a good supplier if it is honest about its role.

Hurain Engitech & Trade is a trading and export company. Our bleaching earth, activated bleaching clay and filter aid are produced by partner plants to the specification you agree, and we handle batch checks, packing, documents and shipping. Because we buy in volume from those plants, our prices are typically lower than an end buyer would get approaching a plant alone. Whoever you buy from, ask which plant produces the material, for a certificate of analysis per batch, and for a sample you can test in your own refinery.

The three products and what each is for

Our refinery clay range has three products: bleaching earth, activated bleaching clay and filter aid. They look similar in a bag but do different jobs, and the choice affects both the oil quality and the cost per tonne of oil.

Bleaching earth: natural and acid-activated

Bleaching earth is a clay, mainly a calcium or magnesium montmorillonite, that adsorbs colour pigments such as carotenoids and chlorophyll, as well as phospholipids, soaps, oxidation products and trace metals from edible and mineral oils. Natural earth works through its natural surface and suits easier oils. Acid-activated earth is treated with mineral acid, which opens the structure, increases the surface area and raises the adsorption of pigment. Most refineries use acid-activated grades for edible oils.

The usual dose is about 0.5 to 2 percent of the oil weight, depending on the oil, the crude quality, the degumming and the colour target. The oil is heated, mixed with the earth under vacuum for a set time, and then filtered. A good earth gives the target colour at the lowest dose, holds little oil in the spent cake and filters quickly. Measure all three, not only the colour.

Activated bleaching clay: for hard-to-bleach oils

Highly acid-activated bleaching clay has a higher surface area and acidity than standard earth, which makes it more effective on oils that are hard to bleach, such as palm oil and rice bran oil, and on oils with high chlorophyll. It delivers good colour and low peroxide at a lower dosage, so the saving on the clay and on oil lost in the spent earth often outweighs the higher price per kilogram.

The trade-off is that very high activity can raise free fatty acid slightly if the oil is bleached too long or too hot, and the cost per kilogram is higher. Run a comparison at several doses: record the colour, the peroxide value, the free fatty acid, the phosphorus and the filtration time. The best grade is the one with the lowest total cost per tonne of finished oil, not the lowest price per bag.

Filter aid: diatomite and perlite

Filter aid is a different material for a different job. Diatomaceous earth (diatomite) and perlite form a porous, rigid cake on the filter that traps fine particles while the liquid flows through. It is used as a precoat on the filter and as a body feed mixed into the liquid. Filter aid is used for oil, sugar, beverages, beer, juice and chemicals wherever a clear, polished filtrate is needed.

Grades differ in flow rate. A coarse grade filters fast but lets finer particles through, and a fine grade gives a clearer filtrate but slows the flow and raises the pressure. Choose the grade by running a trial on your own filter and recording the clarity, the flow rate and the pressure rise. We supply several flow-rate grades in 20 to 25 kg bags.

Reading the specification sheet

A specification sheet should list at least the following. Compare the figures against your own requirement and against the certificate of analysis for each batch.

• Activity: natural, semi-activated or highly acid-activated
• Particle size: typically 75 to 80 percent passing 75 micron (200 mesh)
• Moisture: typically 12 to 15 percent or less
• Bulk density: approximately 500 to 700 g/L
• Free acidity or pH of the slurry
• Oil retention: how much oil the spent earth keeps, which is a direct cost
• Bleaching performance on a standard oil at a stated dose
• Packing: 25 kg bags, or 500 and 1000 kg jumbo bags

Moisture and particle size are easy to check and often reveal a weak supplier. High moisture means you pay for water and it reduces the activity, and uneven particle size slows the filtration.

How to test a sample before you buy a container

Never buy a first container on the spec sheet alone. A laboratory bleaching test costs little and prevents large mistakes. Take a representative sample of your crude or degummed oil, and run the same procedure with each earth you want to compare:

• Heat the oil to your normal bleaching temperature under vacuum
• Add the earth at three doses, for example 0.8, 1.2 and 1.6 percent
• Hold for your normal contact time, usually 20 to 30 minutes, and filter
• Measure the colour (Lovibond red and yellow), the peroxide value, the free fatty acid, the phosphorus and trace metals if you refine for food
• Weigh the spent cake, and record the filtration time

Calculate the cost per tonne of oil for each earth, including the oil lost in the cake. Then ask for a trial lot of one to five tonnes at your plant before you order a full container, and compare the plant result with the lab result.

What affects bleaching performance in your plant

The best earth can still fail if the process is wrong. Check the degumming first, because phosphorus left in the oil poisons the earth and raises the dose. Check the vacuum, because air in the bleacher oxidises the oil and raises the peroxide value. Check the temperature and the contact time, the mixing in the vessel, and the moisture of the earth, which should be controlled so the oil does not foam. Poor filtration, such as torn filter leaves or an uneven cake, shows up as fine earth in the finished oil. When you compare two earths, keep every other variable the same.

Which earth for which oil

Palm oil needs strong carotene removal, so a highly activated clay is usual. Soybean and sunflower oils depend on the degumming, and a standard acid-activated earth normally gives good results. Rapeseed oil often has chlorophyll and needs a high-activity grade. Rice bran oil is hard to bleach and benefits from activated clay and careful pretreatment. For mineral and lubricant oil re-refining, bleaching earth removes colour, acidic compounds and polar impurities. Biodiesel and wax and paraffin purification use similar earths. For juice, beer and sugar, a filter aid is the main tool. Tell us your oil, your process and your target, and we will recommend a grade to test.

Common bleaching problems and what usually causes them

When the finished oil is not right, the earth is blamed first, but the cause is often elsewhere. Use this list to separate a clay problem from a process problem before you complain to the supplier or change the grade.

• Colour is too dark at the normal dose: check the crude quality, the degumming and the moisture of the earth. A new crude lot, or an earth that has absorbed humidity, needs a higher dose.
• Peroxide value is high after bleaching: air is entering the vessel, the vacuum is weak, or the oil stays hot too long before filtration.
• Free fatty acid rises across the bleacher: the earth is very acidic for the oil, the temperature is too high, or the contact time is too long. Try a less acidic grade or a shorter hold.
• Filtration is slow and the pressure climbs: the earth is too fine, the moisture is high, or the filter cloth or leaves are blocked. Check the particle size on the COA.
• Fine earth appears in the finished oil: a leaf is torn, the precoat is uneven, or the polishing filter is missing. This is a filter problem, not a clay problem.
• Oil loss in the spent cake is high: a high-oil-retention earth, too much earth, or too little steam blowing before the cake is discharged.

Keep a simple log for each batch: crude quality, earth lot, dose, temperature, vacuum, contact time, filter pressure and the results of the finished oil. After a few weeks the log shows which variable moves with the problem, and it gives your supplier real data to work with.

Food safety, contaminants and documents for edible oil

If the earth is used for edible oil, it must not add contaminants to the oil. Ask for a statement on heavy metals and on the acid used in the activation, and ask whether the earth is suitable for food use under your country's rules. Our products can be supplied with a food-grade statement or FSSAI-related documentation on request, together with the COA for each batch. Importers in other regions often ask for a declaration of origin, a safety data sheet and sometimes a third-party analysis, so tell us what your authority or your customer requires at the time of the enquiry.

Keep records of which earth lot went into which oil lot. If a customer queries an oil, you can then trace the lot, the COA and the supplier in minutes instead of days.

Spent earth: oil loss, handling and disposal

Spent bleaching earth keeps 20 to 40 percent of oil by weight, depending on the earth and on how well the cake is blown with steam or air. That oil is lost refining yield, so the oil retention of the earth is a real cost and not only a technical figure. A grade with slightly lower activity but much lower oil retention can be cheaper in use.

Spent earth can heat up and catch fire on its own because of the oxidation of the oil it holds, especially in piles. Do not leave spent cake in a heap in the sun. Remove it promptly, keep it away from heat sources and follow the local rules for disposal. Some plants send it for oil recovery, some use it as an additive in cement kilns or brick making, and some compost or landfill it where the rules allow. Ask your local authority which route is permitted.

How to run a trial order with a new supplier

Once the laboratory result is acceptable, a plant trial confirms it. Order one to five tonnes, run it for at least a full shift on a stable crude, and record the dose, the colour, the peroxide value, the filtration cycle time and the oil loss. Run your usual earth for a comparable shift on the same crude for comparison. Agree the pass criteria with the supplier before the trial, in writing, for example the target colour at a given dose with no rise in free fatty acid. If the trial passes, move to a full container with the same specification and ask for a COA with each batch. If it fails, share your log with the supplier; a good supplier will adjust the grade or the dose recommendation or will say honestly that the material is not suited to your oil.

Quality checks to ask for

A reliable supplier will give you the following without being asked twice:

• A certificate of analysis (COA) for every batch, with moisture, particle size, bulk density and activity
• A food-grade statement or FSSAI-related documentation on request, if the earth is used for edible oil
• The batch number printed on each bag, so you can trace any problem
• A retained sample from the shipped batch
• Photographs of the stock, the packing and the loading of the container
• A written replacement or credit policy if the batch fails against the agreed specification

Packing, storage and shipping

Clay absorbs moisture from the air, which lowers its activity, so packing and storage matter. Bags are made of woven polypropylene with a polyethylene liner, in 25 kg size, or as 500 and 1000 kg jumbo bags with a liner and a top cover. Pallets are strapped and wrapped, and containers are checked for dry floors and a clean interior before loading. Keep the material in a dry covered store, off the floor, away from strong odours and solvents, and use the oldest stock first.

The shipping documents normally include the commercial invoice, the packing list, the certificate of origin, the bill of lading and the COA. Confirm the incoterm (FOB, CFR or CIF), the loading port, the destination port and the expected transit time in the quotation. Jumbo bags need a forklift or a crane with a hook at your plant, so tell us your unloading method.

What decides the price

The price depends on the activity, the acid used in the activation, the particle size, the packing, the order quantity and the freight. Compare the cost per tonne of oil, not the price per tonne of clay. A cheaper earth that needs 30 percent more dose and holds more oil in the cake usually costs more in use. A container order with a fixed specification and a steady yearly demand gives the best price, because the plant can plan the production and the freight is spread across more material.

A checklist for choosing your supplier

Before a first order, confirm the following:

• The supplier is honest about whether it is a manufacturer, a trader or an exporter, and names the plant
• A written specification, a COA per batch and a retained sample
• A trial lot or a test sample that you can try in your plant
• A clear packing, labelling and batch-marking description
• The incoterm, the payment terms, the lead time and the claim procedure in writing
• A supplier that answers technical questions about your process

Start with a trial, compare the cost per tonne of oil, and place the container order once the plant results match the lab results.

Get a quotation for bleaching earth and filter aid

Tell us the oil you refine, the daily capacity, your current earth and dose, and your destination port. We will recommend a grade, send a sample and quote the price, the minimum order quantity, the packing and the lead time. Refinery clay can be combined with other products from our engineering and trade ranges in one container, with one set of export documents.