THE CUBA REVIEW 



35 



Filter presses. Central of Francisco Sugar Co., Francisco, Cuba. 

 Bateria de filiros, prensa del Ingenio Francisco, Francisco, Cuba. 



FILTER PRESSES OF TO-DAY 



Owing to the ever increasing demand for 

 ■filter presses, efforts are being made to im- 

 prove _on the original type and as a result 

 some remarkable machines are being 

 offered. 



But it is a peculiar fact that, with all 

 the ingenuity that has been exerted, the 

 "old original" filter press still holds its 

 own with the new t^'pes. 



Of course there have been improvements 

 in the construction of the old types, with- 

 out changing the principles involved. These 

 improvements have resulted in more rapid 

 filtration and less breakage and repairs. 



In some few cases, perhaps most strik- 

 ingly in the cyanidation of gold and silver 

 ores, a new type of press has been evolved 

 which is a decided improvement on the 

 •original. The improvement consists in a 

 method of sluicing out the cake from the 

 frames without opening the press. This 

 eliminates the most objectionable feature 

 in a filter press. 



But there are a number of other, so 

 called, improved filter presses, all of them 

 more or less patented, which are beneficial. 

 Some of the patented presses have been 

 installed and operated side by side with the 

 "old original" type and have shown better 

 results. But let us look a little closer into 

 the reason for this. 



The improved filter press is installed and 

 run by an expert who understands the very 

 best conditions under which it should be 

 operated. He naturally gets the best pos- 

 sible results which this particular press can 

 produce. These results are compared with 

 those obtained from the old original type 

 which is probably run by a handy man who 

 knows no more 'than to force the material 

 into the press as fast as his pump will de- 

 liver it and continue until he can get iio 

 more to filtrate through the press. Now in 

 all probability there is an exact pressure 

 under which this press should be charged 

 which would give the best results. That 

 pressure may be fifteen pounds, or it may 

 be one hundred and fifty, while in pomt 

 of fact the press may have been operated 

 under seventy pounds pressure which 

 might give the worst possible results. But 

 the press has been run that way for the 

 last ten years and there is nobody about 

 the place who has had the authority or 

 interest to try any experiments. 



Therefore, the better results obtamed 

 from the "patented press" are not due to 

 the "patent," but to the fact that the man 

 who was running it "knew how." 



It is prettv safe to say that as perfect a 

 filtration can be obtained with the old type 

 of filter press and at the same cost of 

 operation as with the modern patented 

 article. — Letter to The Cuba Review. 



