CSIRO Leather Research Centre

Hides, Skins and Leather
Adding Value to an Important Co-Product

Hides

Australia is a significant exporter of cattle hides and wet-blue leathers. This has led to considerable interest in the rapid processing of wet-blue with minimisation of the environmental impact of effluent generated. The Leather Research Centre at Clayton has conducted research to produce environmentally-friendly wet-blue and these processes are now available to the industry to utilise in commercial production.

• Traditionally, during the processing to wet-blue, the hair removed from the cattle hides is degraded and discharged to sewer. CSIRO's Sirolime process removes hair intact from hides by using conventional reagents in a novel way which loosens rather than completely degrading the hair. The hair can be filtered and recovered from the processing liquors allowing the liquors to be recycled through the system. By recycling the processing liquors further economic and environmentally-friendly benefits of the Sirolime system can be obtained.

  The process was the first hide hair-saving system developed for drum processing and is the forerunner of a number of commercially developed processes. There are now seven Australian tanneries making use of hair-saving processes, including two using the Sirolime process. Others are expected to follow suit as tanneries re-equip with the latest processing vessels and methods, in preparation for the full impact of more stringent EPA regulations being brought to bear on the industry. The processes have several advantages other than environmental and economic: improved leather quality; simple recycling of processing liquors; and they are generic processes which can be adapted for other types of raw material including kangaroo and very short woolled sheepskins.

• The Leather Research Centre has investigated possible uses for the hair removed in its unhairing processes, the most successful of which is as a soil conditioner and slow release organic nitrogen fertiliser. Development of a commercially viable product is now being undertaken by a private company.

Skins

• A major problem to woolskin processors is felting, which can occur in the wet processing of wool-on sheepskins. The likelihood of felting is increased by the high pile density and fine wool of merino skins. The Siroskin process has been developed and patented by CSIRO to reduce felting. The Siroskin process has great potential to improve the productivity of woolskin tanneries. The process is currently licenced to 3 tanneries and is being trialed at several others.

• The processing of skins after wool removal (fellmongering) is a major problem in Australia, particularly where the acetate method is used. The LRC has developed, and is now commercialising, the "Direct Lime Process" which reduces water consumption by over 40% and time by 50-75%, and produces a flatter, cleaner pelt with significantly improved grain properties.

• The Leather Research Centre is currently undertaking a project to develop a machine to remove wool, for commercial use, from waste sheepskin pieces. The equipment currently available is considered to be unsuitable for merino wool, leaving three million kg of wool being dumped on waste pieces each year. By using the new machine at least 1.5 million kg (worth $3-4 million) could be recovered. A prototype of the new machine has been demonstrated to an abattoir and a machinery supply company, who are potential collaborators with CSIRO. An engineering design company has been given a brief to design a production model and ancillary equipment.

• Hospitals have used medical sheepskins for many years to prevent pressure ulcers in long-term patients. However, in recent years, some hospitals have turned to synthetic `imitation sheepskins' to overcome shrinkage and leather hardening problems experienced when laundering the poor-quality sheepskins that have flooded the market. The synthetic skins do not share the same unique comfort properties as the natural product, and may in fact cause problems of their own. A joint project between the LRC and Fleececraft Industries, supported by the Meat Research Corporation has developed a reliable and commercially acceptable set of performance standards for medical sheepskins. This project has not only defined the standard but has developed the processes to produce medical sheepskins that can withstand multiple washes in excess of 85^oC to ensure sterile skins are returned to patients. The project team has worked with Standards Australia to develop a draft Australian Standard which has now been released for public comment.

The Environment

The Siroskin, Sirolime and Direct Lime processes all involve a more economical use of chemicals and water than conventional procedures, and this in turn reduces the amount of effluent and waste. Waste minimisation and waste disposal have become matters of increasing concern as environment protection authorities around the world become more stringent in their licensing for discharging to sewers.

• With the assistance of a grant from the Department of Science, Industry and Technology, the Leather Research Centre, in collaboration with the former Federated Tanners' Association, has developed a commercially viable salt-free pickling process for hides and skins. This is a significant advance as salt emission in tannery effluent is a major environmental issue, particularly in Australia, and one that will attract harsher penalties as environment protection bodies seek to halt, and indeed reverse, the already considerable soil and waterway damage that has occurred.

• A joint project between the LRC and the Meat Research Corporation has led to the development of a Total Chrome Recycling process. This process recovers all chrome containing liquors which are then clarified to remove all fats, greases and solids, followed by an evaporative process to reduce the liquor volume. The remaining chrome liquor is then directly recycled. The condensate is also recovered for re-use elsewhere in the process.

  Effluent treatment costs normally associated with chrome liquors are virtually eliminated and substantial chemical savings are achieved for chrome and salt.

• EPA Regulations in some areas have also focussed on the emission of ammonium salts which have traditionally been used during the deliming process. LRC research into replacing ammonium salts with carbon dioxide for deliming has established a commercially viable, more environmentally-friendly process which is also cheaper than the conventional deliming.

Consultancy

As well as continually striving to improve the processes used in the leather industry through strategic research, the Leather Research Centre also responds to specific problems faced by individual companies. These services range from engineering problems in tanneries, to advice on how to conform to EPA regulations, to the analysis and solution of problems associated with all types of leathers.

The LRC is able to analyse leathers and processing solutions for dyestuffs, fatliquors, tanning agents and auxiliaries. Of particular importance is the analysis of azo-dyestuffs which are now regarded as environmentally unacceptable in many countries.

Last update 2 August, 1996