Filter Presses for the Pharmaceutical Industry: Selection, Quality and Efficiency Guaranteed

In the pharmaceutical industry, the final drug substance (active pharmaceutical ingredient, API) and key synthetic intermediates are mainly isolated as crystalline solids.

Considerable effort is invested in the crystallisation process to produce a crystalline solid with the necessary chemical quality together with the appropriate physical properties (filterability, product size, uniformity, etc.) for isolation and further processing in the manufacture of the pharmaceutical product.

However, these properties are often compromised during API isolation through filtration, washing and drying.

These isolation processes pose significant challenges for the production of crystals with the desired physical properties, avoiding granulation, crystal breakage or precipitation of dissolved products and impurities.

The pharmaceutical industry demands a high standard of purity for the final API. To meet this standard, cake washing after filtration is an essential step.

After filtration, the residual stock solution (crystallisation solvent containing unreacted raw materials and unacceptable by-products) is retained and trapped within the porous structure of the solid bed.

If this stock solution is not removed before the subsequent drying process, the dissolved material will be deposited on the surfaces of the product crystals, resulting in the presence of impurities in the final product.

Washing is therefore a vital purification step to remove impurities from the filter cake. Filter cake washing is generally achieved using the same driving force (centrifugal, pressure and vacuum) as filtration, and is carried out on the same process equipment used for filtration, minimising the need for additional equipment.

What is meant by a pressure filter for pharmaceutical production?

Filter presses, also known as filter presses, are filtration equipment used in various industries, including the pharmaceutical industry, to separate liquids from solids in suspensions.

This equipment works by applying pressure to force the solids from the liquid through a filter medium, usually a series of plates and frames.

In the pharmaceutical industry, efficiency and purity are paramount. Filter presses play a crucial role in the separation of liquids and solids, ensuring that dewatering processes meet the highest standards.

Designed specifically for pharmaceutical needs, these units can be adapted to different sludge types and volumes. They can optimise your pharmaceutical processes, guaranteeing economical and uncomplicated dewatering performance.

Operation of filter presses in the pharmaceutical industry

Filter Presses in the pharmaceutical industry are a proven and reliable technology for the efficient separation of liquids and solids in a wide variety of applications.

The principle of operation of these filters is based on pumping sludge into the machine, evenly distributing the solids during the filling cycle. These solids accumulate on the filter cloth, forming the so-called filter cake, while the filtered liquid exits through the filter plates into the collector, producing clean filtered water.

Automation is a key feature of these filters, as they operate with a self-contained panel and an integrated programmable PLC, allowing full process control and ensuring consistent filtration results even under varying process conditions. In addition, the single cloth system makes maintenance easy, with cloth changes taking only 30 minutes and not requiring equipment downtime.

The process itself consists of several stages: feeding, filtration, pressure application, washing if necessary and finally, discharge of the filter cake. This technology ensures efficient separation of liquids and solids in the pharmaceutical industry, meeting the highest standards of quality and purity required by GMP and FDA regulations.

Stages of the filtration process

• FeedingThe liquid and solid suspension is pumped or poured into the pressure filter.
• FiltrationThe plates and frames of the pressure filter are covered with filter cloths. The suspension flows through these cloths, and the solid particles are trapped in them, forming a filter cake on the surface of the cloths.
• Pressure ApplicationPressure is applied to the filter to compress the filter cake, which helps to expel more liquid and dry the cake.
• WashingIf necessary, the filter cake can be washed with water or solvents to remove residual impurities.
• DownloadFinally, the filter cake is removed from the filter press and discarded, and the filtered liquid is collected as product.

Main benefits of Filter Presses in the pharmaceutical industry

Filter presses in the pharmaceutical industry provide a number of essential benefits that align perfectly with production needs, stringent regulations and product quality. These benefits include:

• Highly Effective WashingFilter presses allow efficient washing of the cakes, even with multiple washing stages, possibly in countercurrent. This ensures complete removal of impurities and unwanted residues.
• Residual Moisture ReductionThese systems minimise the remaining moisture in the filter cake, which includes efficient drying processes and a 100% discharge from the cake. This is essential to maintain the quality and purity of the final product.
• Integrated ProcessingFilter presses allow multi-stage processing in a single unit, resulting in increased automation and process optimisation. In addition, they ensure product safety and traceability, eliminating human impact on the process.
• Adaptability to Production NeedsThese systems are highly adaptable to production capacity needs, and comply with specific regulations such as ATEX for solvent-based processes. They are fully enclosed and can operate in controlled environments (HEPA) to comply with GMP and FDA regulations.
• Handling of Sensitive ParticulatesFilter presses can process ultrafine and sensitive particles with low suspended solids content. They also undergo intensive testing and piloting to ensure optimum process performance.

Filter presses are a versatile and highly effective solution that addresses critical challenges in the pharmaceutical industry, ensuring quality, efficiency and regulatory compliance at every stage of the production process.

Applications of Filter Presses in the Pharmaceutical Industry

Filter Presses are essential in pharmaceutical production for the separation of solids and liquids at various stages of the process, such as the production of active pharmaceutical ingredients (APIs) and final products. Some of their common applications in the pharmaceutical industry include:

Filter presses in crystallisation processes

Filter Presses play a crucial role in crystallisation, a key unit operation and an important processing and development step within the pharmaceutical industry. This process is used in the separation and purification of intermediates and Active Pharmaceutical Ingredients (APIs), and more than 80 % of pharmaceutical products involve at least one crystallisation step.

Let's imagine you are in the middle of synthesising a new drug and have managed to obtain solid crystals of the API in a liquid suspension after the chemical process. At this crucial point, Filter Presses come into play to isolate these valuable crystals. The suspension is fed into the filter, and the applied pressure allows the crystals to separate from the mother liquid. This process is essential to ensure the quality and purity of the final products in the pharmaceutical industry.

In addition to the separation of solid crystals, Filter Presses are also effective in retaining impurities present in the suspension along with the crystals. This results in a cleaner, higher purity product, which meets the industry's stringent quality standards.

Filter Presses not only contribute to separation and purification, but also enable the recovery of valuable stock solutions containing reagents and chemicals. This recovery is essential for resource efficiency and waste minimisation in pharmaceutical production.

Crystallisation is a fundamental process in the pharmaceutical industry, and Filter Presses play an essential role in this process by facilitating the efficient separation of solid crystals from the mother liquid, thus ensuring the quality and purity of pharmaceutical products reaching patients.

Filter cake washing

After crystallisation, the active pharmaceutical ingredient (API) must be separated from the stock solution and impurities. The separation of API crystals is usually done by pressure filtration, and filter cake washing becomes a crucial step in pharmaceutical processing. High purity is a fundamental requirement, and inefficient washing of API crystals can affect the quality properties of the final drug, leading to potential problems in downstream processing steps.

The application of filter cake washing aims to remove impurities and stock solution from the filter cake by using a pure, miscible washing solvent. The number of washing steps required and the washing solvent vary according to the specific process.

Filter cake wash design and operation requires careful evaluation. API solubility in the wash solvent is undesirable, as it can reduce product yield. Therefore, the selection of the wash solvent must be carefully made to displace the cake stock solution while minimising product dissolution.

A thorough understanding of the process is essential. The development of washing profiles helps to understand the washing regime and to find the optimum conditions for maximum washing efficiency. Refractive index measurement has proven to be a valuable tool in the development, monitoring and control of filter cake washing operations. It is used, for example, to understand the impact of process and product variations, to create wash profiles and to find the most suitable washing solvent.

Filter cake washing has several key objectives:

• Removal of impuritiesThe impurities present in the cake, such as unwanted by-products or uncrystallised particles, are washed out and removed. This is crucial to obtain a final product with the required purity.
• Removal of residual solventsSolvents used during crystallisation and filtration can be trapped in the cake. Washing ensures that these solvents are completely removed, avoiding undesirable residues in the final product.
• Optimisation of purityBy removing impurities and residual solvents, washing contributes to a purer, high quality product that meets pharmaceutical standards.
• Preparation for later stagesThe washed and purified product is ready for the subsequent stages of the pharmaceutical manufacturing process, including drying, mixing and formulation. A clean product is essential to avoid cross-contamination and to ensure the efficacy of the medicines.

Filter cake washing is a critical stage in pharmaceutical production. Filter Presses play an essential role in facilitating this process by ensuring efficient and thorough filter cake washing, which, in turn, contributes to high quality and high purity pharmaceutical products.

Filter cake drying

In certain circumstances, the filtration process does not end with the simple separation of solids and liquids in the filter cake. In many cases, it is essential to carry out an additional step, known as filter cake drying, to remove the excess liquid and obtain a final product with the desired properties.

Filter Presses play a key role in this process, as they offer the ability to efficiently apply controlled pressure to the filter cake. This pressure exerted on the filter cake has a clear purpose: to expel the liquid trapped in the porous structure of the filtered solids. Through this drying operation, the residual moisture in the cake is significantly reduced, which is especially critical in the pharmaceutical industry where exceptional standards of purity and quality are demanded.

Filter cake drying with Filter Presses results in several key benefits:

• Improving product qualityEffective removal of residual liquid ensures that crystalline solids or product particles retain their desired physical and chemical properties, preventing degradation or the formation of unwanted agglomerates.
• Increased processing efficiencyBy reducing the moisture in the cake, the drying time is accelerated, resulting in shorter production cycles and higher overall process efficiency.
• Compliance with quality standardsIn the pharmaceutical industry, where purity is essential, cake drying with Filter Presses ensures that the final product meets the most stringent quality standards, avoiding the presence of impurities or moisture-related contaminants.
• Waste minimisationEfficient liquid extraction reduces waste generation and can have a positive impact on the sustainability of the process.

Filter cake drying using Filter Presses is a critical operation in the pharmaceutical industry and other sectors requiring high purity and quality end products. This phase of the filtration process ensures that solids are presented in the desired form and meet the most demanding specifications, thus contributing to the success and efficiency of pharmaceutical and other chemical and industrial material production.

Purification of pharmaceutical products with filter presses 

The purification of pharmaceutical products is a critical stage in the production chain of the pharmaceutical industry. Before medicines reach patients, it is essential to ensure that they are free of impurities and meet the highest standards of quality and purity. In this context, Pressure Filters play a key role in providing an efficient and reliable means of carrying out the purification of pharmaceutical products.

Pharmaceutical Purification Process

The purification of pharmaceutical products is a process that involves the removal of solid impurities and contaminants present in the active substance of the drug, known as Active Pharmaceutical Ingredient (API). These impurities may include unwanted particles, undesirable chemical compounds, reaction by-products, among others.

Role of Pressure Filters in the purification of pharmaceutical products

Pressure filters are widely used in the pharmaceutical industry due to their proven effectiveness in solid-liquid separation. Here are some key reasons why this equipment is essential in the pharmaceutical purification process:

• Removal of impuritiesPressure filters allow effective separation of solid impurities present in the API. This ensures that the final product is free of unwanted particles that could affect the safety and efficacy of the medicinal product.
• Quality PreservationPressure filter purification helps preserve API quality by selectively removing unwanted substances. This is essential to ensure that the final product meets the most stringent quality standards.
• Regulatory ComplianceThe pharmaceutical industry is subject to strict regulations that demand high levels of purity and quality. Pressure Filters are a reliable tool to comply with these regulations and ensure that pharmaceutical products are safe for consumption.

Filter Presses are essential in the pharmaceutical industry to ensure compliance with GMP (Good Manufacturing Practices) and FDA (Food and Drug Administration) regulations for the separation and purification of pharmaceutical products.

Filter Presses play an essential role in ensuring regulatory compliance in the pharmaceutical industry. Their ability to effectively separate solids and liquids contributes significantly to the quality control and purity of pharmaceutical products, a fundamental requirement under GMP and FDA regulations.

In addition, these filters minimise cross-contamination and ensure proper documentation and traceability, which supports regulatory compliance.

Process validation and personnel safety measures are key elements supported by Filter Presses. In addition, their ability to adapt to specific regulations, such as those of the EMA in Europe, ensures compliance with global standards of quality and safety in pharmaceutical production.

• Improving EfficiencyPressure Filters are known for their efficiency in solid-liquid separation, which translates into shorter processing times and higher productivity in the production plant.
• PersonalisationThe equipment can be tailored to the specific purification needs of each pharmaceutical product, ensuring a precise and effective approach to removing impurities.

Filter presses play a key role in pharmaceutical production by enabling efficient separation and purification of solids and liquids. They help ensure the quality and purity of pharmaceutical products, meeting exacting industry standards.

What to consider when selecting Filter Presses for pharmaceutical processes

When selecting Filter Presses in the pharmaceutical industry, it is essential to consider several key aspects based on the information provided in the text:

• Filtration areaFilter Presses: Assessing the specific production needs and the volume of liquid to be processed is essential. Depending on the required capacity, different Filter Press models can be selected with filtration areas varying from 1.6 m² to 12.6 m². It is important to consider the desired processing capacity.
• Chamber volumeThe volume of the filter chamber, which varies according to the size of the filter plates (45 mm or 60 mm), must be taken into account. This will affect the amount of solids and liquids that can be processed in each filtration cycle.
• Filter plate sizeThe size of the filter plate is relevant for determining the overall dimensions of the pressure filter. This must be adjusted to the space limitations in the production plant.
• Filter dimensionsFilter length, height and width consideration is essential to ensure that the filter fits properly in the working area of the pharmaceutical plant and allows for efficient operation.
• Filter weight: Assessing the weight of the filter is important to ensure that the plant infrastructure can support it in a safe and stable manner.
• Electrical requirements: Take into account the electrical requirements for the hydraulic unit, the pressurised water pump and other components related to the operation of the pressure filter.
• Floor area requiredDetermining the space required to install the pressure filter in the plant is essential for proper layout and efficient operation.
• Maintenance and spare partsConsider the availability of spare parts and ease of maintenance to ensure continuous trouble-free operation of the pressure filter.

When selecting Filter Presses in the pharmaceutical industry, factors such as processing capacity, filter dimensions, electrical requirements and available plant space must be taken into account to ensure efficient and safe operation to meet specific production needs.

Larox® PF Automatic Pressure Filters for the Pharmaceutical Industry

The Larox® PF Automatic Pressure Filters by METSO are the perfect choice to ensure efficient and reliable pharmaceutical production. Their range of models offers different capacities, designed to suit your specific needs. With a focus on ease of maintenance and consistent results, they provide you with a solution with the following outstanding benefits:

• Proven capability with efficiency and reliability.
• Reduced operating costs and competitiveness in the total cost of capital.
• Production of dry, homogeneous and efficient solids washing filter cake.
• Fully automatic operation, with self-diagnosis and flexibility.
• Saves space on the ground for a better optimisation of your plant.

Trust METSO to select the right filter, design your plant and achieve a smooth pharmaceutical operation. Maximise your efficiency and quality with Larox® PF filters!