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• Luis Miguel La Torre

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DESIGN CONSIDERATIONS FOR MERRILL-CROWE PLANTS

R , L. Atwood

R. H. Atwood Crater Exploration Salt Lake City, Utah

For ~ ~ e s e n t a t i oat n the SME-AIME Fall Meeting Albuquerque, New Mexico - October 16-18, 1985

Permission is hereby given to publish with appropriate acknowDedgrnen9s, excerpts or summaries not to exceed one-fourth QB the entire text of the paper. Permission to print in more extended form subsequent to publication by the Institute must be obtained from the Executive Director of the Society of Mining Engineers of AIME. I% and when this p a p r Is published by the Society 0 %Mining Engineers of AIME, it may e m m y certain charages made by agreement between the Technical Publications CsmmitSee and ithe author, so that the form in which it appears hare is not necessarlty that in which it may be published later. k s e pmprints are available for sale. Mati orders to PREPWiNTS, Society of Mining Engineers, Caller No. D, liftleton, Colorado 80"12'7.

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PREPRINT A ~ . l A l l k A B l b lLIST ~ IS PUBLISHED PERIODICALLY IN MlNlNG ENGINEERING I

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Design Considerations f o r Mrrill-Crowe P l a n t s I.

Abstract

This paper discusses t h e X e t a l l u r g i c a l and .Chnufacturing i n ~ u t t o ~ P k r r i l l - C r a ~pel a n t s . Toplcs t r e a t e d a r e pregnant s o l u t i o n chemistry, c l a r i f i c a t i o n , degassing, z i n c a d d i t i o n , product f i l t r a t i o n , accounting, and c o s t s . 11.

Introduction

a r u l e of thumb, one should have a t least 2.2x103 m3/s (1.5 f o o t squared Fer c g n ) of pregnant feed. X o m l l y there a r e bna p r e f l l ters arranged such t h a t production does n o t s t o p during c l e a n up and precoating of t h e p r e filters The s o l i d s rerrsved f r m t h e s e f i l t e r s sre of no value and can be discarded. ? ? o m 1 p r a c t i c e is t o discharge them t o tails. C l a i r i f i c a t i o n f i l t e r s can k c m e plugged by excessive a m u n t s of slimes o r t h e a d d i t i o n of t o o much f l c c u l a n t .

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The removal of metal values f r m cyanide s o l u t i o n s , f o r t u n a t e l y , can be done i n s e v e r a l ways. The o l d e s t p r a c t i c e d method i s , cerenta t i o n with z i n c , o r Merrill-Crowe. Vammn degassing is done i n a p c k e d towThe o r i g i n a l p a t e n t f o r recovery of gold er. The c l a r i f i e d pregnant s o l u t i o n is i n t r o and s i l v e r f r m cyanide solutions described duced i n t o t h e t o p of t h e tower and p r c o l a w p r e c i p i t a t i o n with z l n c K4, I n c .

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Feed R a t e

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