The development of automatic pressure filtration at Larox

@OMATIC PRESSURE FILTRATION The development of automatic pressure fi ltration at Larox Automatic pressure filtration is a very important operation in many processing applications. Larox has grown into an internationally recognised leader with its innovative development programme in this rugged and widely applied technology. Here we look at the recent history and progress of this forward- looking Finnish company. A lmost two decades ago Mr Nuutti Vartiainen, the founder of the Finnish company Larox, had an opportunity to develop a technical solution into a sellable product. Changing the direction of filtration ~rom horizontal to vertical made it possible 1o automate pressure f i l tration in an efficient way. In addition, several other advantages were discovered: it was very important to achieve higher solids con- lents, and to include efficient washing of lhe cake. Since this solution was developed il has gained an increasing number of users who have been convinced of its effectiveness, and Larox is an internationally acknowl- ~dged leader with its vertical automatic pressure filters. Today Larox, with its headquarters and main production facilities in Lappeenranta, is an internationally operating designer and manufacturer of environmentally friendly and energy-saving machinery and equip- ment for the process industries and water ~reatment plants. The company specialises in developing methods and equipment for solid/liquid separation, as well as valves and flow systems, for demanding fluid, slurry and bulk material handling applica- tions. The international breakthrough was the Filtration & Separation February 1995 Surrc~unded by lakes, the Larox production facil ity in Lappeenranta in southeastern Finland is possibly the most beautifully located solid/l iquid separation machinery manufacturing plant in the world. introduction of automatic vertical pressure filtration almost 20 years ago. The funda- mental innovation with Larox automatic pressure filtration was the change in the direction of filtration from horizontal to vertical, i.e. the filtration chambers lie horizontally in the form of a tower. This enabled the use of a long, endless filter cloth as a conveying belt, making possible auto- matic filter cake discharge and unmanned operation. In addition to production economies, from its introduction it has given a high efficiency of solid/liquid separation and good washing characteristics. The solution has been successfully used in the mineral processing and metallurgical industries, in chemicals and foodstuffs, and in the pharmaceutical and pulp/paper industries throughout the world. This technology has also shown its capabilities for cost-efficient, high-quality dewatering in specialised and demanding effluent treatment applications. Quality in the first hand Recently there has been a very great emphasis in Larox on its commitment to The first delivery of Larox Power PF class automatic pressure filters was to Finminerals for talc dewatering. This Power PF 120 with its 2 • 120 m f i l tenng area has now been ~n use for .four years. 0015-1882/95/US$7.00 ~'~ 1995 Elsevier Science Lid quality. A significant milestone was the ISO 9001 quality certificate granted to Larox in October 1993. A year later the quality system is the personal tool for everyone in the company in his or her own work. The significance of the ISO certificate is underlined especially in international com- petition, because it ensures a company's high operational quality level, resulting in high-quality products. A supplier with a certified quality system has more to offer customers than just a guod reputation, as its quality assurance system has been passed by an impartial inspection following standard procedures,' says Mr Timo Vartiai- nen, the president of Larox Group. 'Continuous product development based on customer requirements is an integral part of a company's success worldwide. Larox specialises in solving its customers' process problems. The understanding of the customers' needs is completely irreplaceable by any quality system, no matter how advanced. A leading position in the market can be achieved and secured only by continuous and thorough customer con- tacts,' he continues. Worldwide sales supported by service from start to finish From the very beginning it was clear that worldwide success in sales would not be possible without back-up for the products. A worldwide sales network was established ve~ early in the company's history. Today its 119 OMATIC PRESSURE FILTRATION main market areas -- North America, Australia, most of the central European countries, Chile and southern Africa -- are covered by their own Larox subsidiar ies and ~ales offices. In other countries the company is represented by local agents. The Larox principle is that close representat ion is needed before a sale can take place. In addit ion to conventional after-sales services, Larox supports its customers with extens ive pre-sa les services. Since the automatic pressure filter is part of a larger process, which usually has difficult demands such as high temperatures, corrosive acid or a lkal i env i ronments and other typical iwocess requirements, it is essential to test and s imulate the process in a laboratory or at pi lot-plant scale, to facil itate selection of t he most appropr iate filter equipment. For test ing purposes Larox has a world- wide network of test f i ltration laboratories. Most of the representatives have facil it ies to run f i ltration tests, and the field tests can be suppor ted by tes ts in the company 's research centre at the main p lant in Lappeenranta. Larox test engineers also travel worldwide to assist local representa- l ives in the i r tes t work, and so the company's global experience is made avail- able to the benefit of the customer. In some cases it is also worth performing pi lot-plant-scale production tests, in order to ensure the accuracy of the full-scale process results. For these purposes several conta iner -mounted pi lot pressure f i l ter units are available to be transported any- where in the world to the customer. From the test results the dimensioning and selection of fi lter type and size are derived. Proper test ing also allows Larox to guarantee the process results, which is a greatly appreciated feature in the purchase of process equipment. When a Larox fi lter is delivered, instal la- 120 Cooperation with a new customer starts with test f i l t rat ion o f the s lurry us ing a Larox PF 0.1; this s imple min ia ture laboratory pressure f i l ter accurately s imulates the real s ize f i lter. tion assistance and operat ing and main- tenance t ra in ing are inc luded in the package, and given by a service engineer special ised in that application. Often custo- mers also like to have a service contract, to secure trouble-free operation of the filtra- tion equipment. The after-sales manager, Mr Jaakko Happonen, notes: 'Good after-sales service means that every eventual ity can be covered. This means fast and reliable spare parts deliveries, detai led documentat ion, ins ta l la t ion and s tar t -up serv ices and technical services. The customers must also be kept up-to-date with progress.' Continuous product development secures the future A key factor in keeping Larox in the forefront of the industry is its extensive product development. 'We use ten per cent of our turnover in research and develop- ment work. Its main task is to enlarge the usage area of automatic, vertical, pressure filtration, the ut i l isat ion of new technologies and to increase the efficiency and economy of the company's products for the benefit of its customers,' says Timo Vartiaineu. The results are clearly apparent. During the past few years the main task has been to widen the range of capacities. The first step was to introduce the hydraulic normal-sized PF pressure filters at the end of the 1980s. The use of a hydraulic closing mechanism resulted in better construction of the whole filter unit, and increased the size variat ions up to 38 m 2. The next development was the launch of the larger Power PF pressure filter series. Specially designed for high capacities, the largest Power PF models have a fi ltration area of 144 m 2, and can achieve capacit ies as high as 150 tonnes/hour. Deliveries have taken p lace to talc, copper and zinc concentrate dewater ing applications. The company's latest development in pressure fi ltration is the Larox Minimax, which is intended for smaller-capacity and spec ia l ised so l id / l iqu id separat ion pro- cesses. The Minimax is avai lable in four sizes, with f i ltration areas from 1.6 m ~ to 6.3 m 2. A special model based on the Minimax, the Larox Sulfapress, has been developed for gas 'sweetening' and hydrogen sulphide removal processes. Applications in chemicals, pharmaceuticals and foodstuffs Larox horizontal pressure f i l tration has been used for var ious app l i ca t ions in d i f fe rent indust r ies , espec ia l l y in the mining industry. However, the use of this technology has increasingly spread to the chemical industry, in which the variety of The most recent Larox Power PF del iveries have been to Aust ra l ia fo r the Pa~uminco Group. Two Lat~.~: Power PF 60 uni ts are shown ready fo r despatch. February 1995 Filtration & Separation applications is very wide. Over the years the company's automatic pressure filters hmze been installed in many applications where the separation efficiency and especially efficient cake washing are important fac- tors. In general the company's competitive edge has been the overall process economy of its filters, and its improvement of the quality of the clients' products and pro- cesses in an environmental friendly way. Fermentation processes In numerous processes the chemical or pharmaceutical product is produced by fermentat ion. The first step after the fermentation itself is the separation of the liquid from the mash or broth. Traditionally vacuum filtration and centrifuges have been used in these processes because of their continuous operation, even though the results have not necessarily been the best possible. In the last couple of years Larox has brought its fi ltration expert ise to this industry, introducing better process results compared to previous technologies. Penicil- lin is a .typical example. Several positive results have been obtained when the fermentation broth is filtered with Larox filters: [] The filter cake solids reach 27% w/w, i.e. the filter cake is so dry that it can be handled in solid form instead of as a slurry, as with previous technologies. This results in reduced costs for cake handling. ~:] The loss of penicil l in is less than 0.5--1.0%. In vacuum filtration it has been as high as 2--5%. This clearly indicates a significant improvement in the overall process efficiency. [] The solids in the filtrate are less than 100 mg/1, which improves downstream processes such as extraction. These benefits have been demonstrated at several operational installations around the world. Starch The company's pressure filtration technol- ogy has been successfully utilised in several Filtration & Separation gebruary 1995 I OMATIC PRESSURE FILTRATION Part of the user f r iendl iness is the touch-screen control panel, which provides the operator with real-t ime informat ion on the process, and which also d isplays instructions for different operating situations, inc luding error cases. It can also be connected to systems control l ing the whole process. different starch processing applications, especially with wheat starch. Significant advantages are provided over the standard technology -- i.e. centrifuges -- both in starch dewatering and washing. The solid/ liquid separation results obtained are better in all most important parameters, such as 4% greater dry solids in the starch cake, better washing results and a clearer filtrate. The latest proof of Larox technology will be a large new installation, comprising six filter units, at one of the leading starch manufacturers in the United States. Elementary sulphur from gas treatment There are a number of different gas streams in the chemical industry and in energy production, where hydrogen sulphide must be removed from the gas stream before further use or release to atmosphere. The most environmentally friendly meth- ods process hydrogen sulphide into elemen- tary sulphur in solid form. This sulphur can be used directly -- i.e. with no further treatment -- as a raw material for various subsequent processes, or it can be safely dumped at a landfill site. These processes need an efficient solid sulphur removal process which is able to produce sulphur pure enough for subse- quent use. Larox automatic pressure filtra- tion has been shown to be a very effective solution -- for example, in the Sulferox process developed by Dow Chemicals and Shell. This process has been used success- fully in 'sweetening' (the term used for the H2S removal process) of gas s t reams produced in oil refineries, natural gas and geothermal energy production. Larox filtra- tion technology has proven its fully auto- matic operation and efficiency in several installations. In 1994 the company intro- duced its Sulfapress for these processes. Based on its Minimax design, it is specially designed for these specific application requirements. Metal concentrates and minerals is another strong area Even though the very first deliveries of Larox pressure filters were for the chemical industry, in its early days metal and minerals concentrates were the biggest application area for the company's equip- ment. This is no surprise, since automatic vertical pressure filtration gave such a higher solids content, that in many cases thermal dryers were no longer required to achieve the required moisture level. This meant significant energy savings, as well as reduced pollution levels. Furthermore, as a result of the efficient cake washing proper- ties of vertical pressure filtration, a higher rate of recovery of precious metals was achieved in hydrometallurgical processes. Over the last two years Power PF class filters have gained a good foothold in the metals and minerals processing industries. A recent delivery was for the Rudna copper mine in Poland, where the first unit from a total of three Power PF 132/144s has already been in operation for two years; the second and third units will be taken into use during 1995. In Rudna the main reason to switch over to automat ic pressure filtration was the far better solids content (increased by more than 10%) than with the previous vacuum disc filters, and a total of nine thermal drum dryers (out of 12) could be substituted. In addition to cost savings this was also a remarkable improvement for the local environment. In addition, in Australia a total of six Power PF class filter units will be commis- sioned in three zinc concentrators during 1995. The most recent new application for the company's automatic vertical pressure fil- ters in the mining industry is in small-scale solid/liquid separation, such as dewatering of gold and silver concentrates. This results from the widening of the product range with the smaller Minimax filters. Two units have already been delivered to Chile for this type of application. In addition to mining and metallurgy, minerals producers commonly use Larox filters for talc and calcium carbonate processing; an example is PCC. GOOd prospects 'Larox's future prospects regarding growth and profitability are excellent. In order to maximise future possibilities, several devel- opment projects have been started, which will improve the quality of the service and guarantee positive areas where we are world leaders. This all for the benefit of our customers, ' says Timo Vartiainen. 'For instance, previous product range enlarge- ments enabled Larox to access areas which have not been realistic before.' Now, when the world economy is starting to recover from recession, Larox seems to b(. ready to push forward. The product range covers most of the capacity needs, recem installations in new application areas have been successful, and operations with the certified quality system have been trimmed to achieve results. Larox believes it is a partner for those who need advanced solid, liquid separation. 121