一、概述

砂(sha)金(jin)(jin)(jin)礦(kuang)(kuang)中(zhong)除含金(jin)(jin)(jin)外、另含多(duo)種(zhong)重(zhong)(zhong)礦(kuang)(kuang)物、與金(jin)(jin)(jin)伴生常(chang)見的有(you)磁鐵(tie)礦(kuang)(kuang)、鈦(tai)鐵(tie)礦(kuang)(kuang)、金(jin)(jin)(jin)紅石(shi)、鋯英石(shi)、赤鐵(tie)礦(kuang)(kuang)、鉻鐵(tie)、鉑(bo)、銥、辰砂(sha)、鎢、錳、錫、金(jin)(jin)(jin)剛石(shi)、剛玉、方(fang)鉛礦(kuang)(kuang)等重(zhong)(zhong)礦(kuang)(kuang)物含量1—3kg/m3。其(qi)余為礫(li)石(shi)、卵石(shi)和泥(ni)土。泥(ni)土在(zai)選(xuan)(xuan)金(jin)(jin)(jin)中(zhong)不利回收細粒(li)金(jin)(jin)(jin)。選(xuan)(xuan)別過程(cheng)中(zhong)應設(she)法(fa)(fa)碎解、篩分、脫泥(ni)。重(zhong)(zhong)礦(kuang)(kuang)物元素只要上指標(biao)應考慮綜合(he)(he)回收工藝(yi)。砂(sha)金(jin)(jin)(jin)品(pin)位正常(chang)在(zai)0.3—10g/t,粒(li)度0.2—2mm，形狀(zhuang)為粒(li)狀(zhuang)、片狀(zhuang)、枝狀(zhuang)、針狀(zhuang)等。選(xuan)(xuan)礦(kuang)(kuang)原(yuan)則優先采用(yong)重(zhong)(zhong)選(xuan)(xuan)法(fa)(fa)，繼而考慮綜合(he)(he)回收其(qi)他重(zhong)(zhong)礦(kuang)(kuang)物，可采用(yong)重(zhong)(zhong)、浮、混汞、磁選(xuan)(xuan)等聯合(he)(he)作業彼(bi)此(ci)分離各種(zhong)礦(kuang)(kuang)物。

二、選金工藝設備

砂金選礦設(she)備(bei)及工藝(yi)多種方式：離心選礦機、圓錐選礦機、跳汰機、螺旋溜槽、搖床、固定(ding)溜槽、振動(dong)溜槽等配套。

據多年設備使用反饋，選(xuan)礦穩(wen)定性(xing)較好(hao)的是采(cai)用砂(sha)金(jin)雙層組合(he)溜槽、生產(chan)能力(li)大、成本低、占地(di)面積小(xiao)、可拆裝搬動(dong)、移(yi)動(dong)性(xing)強(qiang)。粗(cu)選(xuan)回收(shou)率(lv)80—85% 、精選(xuan)回收(shou)率(lv)90—95%。

生產(chan)過(guo)程：用推土機(ji)、挖掘機(ji)，將砂(sha)金(jin)原礦(kuang)(kuang)送入篩(shai)機(ji)碎解、分級脫泥后，≤60mm礦(kuang)(kuang)石(shi)送入溜槽(cao)(cao)的(de)供(gong)礦(kuang)(kuang)箱(xiang)，以大量高(gao)壓水噴沖礦(kuang)(kuang)砂(sha)，充(chong)分洗選下，礦(kuang)(kuang)漿流入帶有篩(shai)孔的(de)臺板上(shang)篩(shai)選，20-60mm礦(kuang)(kuang)石(shi)進入溜槽(cao)(cao)中間槽(cao)(cao)選礦(kuang)(kuang)。

篩下產(chan)品≤20mm礦(kuang)(kuang)砂被分配(pei)到下層(ceng)兩側溜槽、槽底設有格(ge)條(tiao)及(ji)氈(zhan)墊(dian)，礦(kuang)(kuang)漿流經格(ge)條(tiao)氈(zhan)墊(dian)時，按密度(du)和(he)粒度(du)進行分層(ceng)，金粒及(ji)重礦(kuang)(kuang)物(wu)被富集在氈(zhan)墊(dian)上，溜槽上設立防(fang)盜(dao)門鎖(suo)，換(huan)班清理氈(zhan)墊(dian)時，由專人(ren)開鎖(suo)。清理出(chu)來的精礦(kuang)(kuang)轉(zhuan)入振(zhen)動溜槽精選，經搖(yao)床分離金砂及(ji)其他重礦(kuang)(kuang)物(wu)，化學(xue)處理后(hou)送冶煉爐出(chu)品。

Placer gold processing equipment

1. General

Placer Gold contains a number of heavy minerals in addition to gold and is commonly associated with magnetite ,ilmenite, rutile, zirconium quartz, hematite, ferrochrome, iridium, cinnabar, tungsten, manganese, tin, diamond, corundum, calcite and other heavy minerals with its content being 1-3ktg/m3 as well as gravel, cobble and soil. Presence of soil is not favorable for recovering fine gold in the process of gold dressing. Efforts should be made to conduct breaking, screening and desliming operations in the period of separation. Consideration should be given to comprehensively recovering the heavy metal elements with desirable indexes available. Normally, placer gold occurs in granular, flaky, branched and needle shapes with 0.3-10g/t in grade and 0.2-2mm in size, Preference should be give to gravity concentration in ore dressing. Also, consideration should be given to comprehensively recovering other heavy minerals by combined use of gravity, flotation, amalgamation, magnetic separation processes to separate minerals.

2. Process equipment for processing placer gold

Placer gold dressing equipment and process are available in a number of types: centrifugal separator, cone separator and jig complete with spiral chute, table, stationary chute, vibrating chute and others.

Feedbacks from customers for the equipment application over years show that relatively stable in ore dressing is to introduce placer gold two-layer combined chute with large production capacity , low costs. less use of land , mountingability and dismountingability, removability. Recovery rate for roughing is 80 – 85% and recovery rate for cleaning 90 –95%.

Production Process: Run-of-mine placer gold is hauled by bulldozer and excavator into screening machine for breaking, classification and desliming prior to being delivered into ore box of chute, where placer gold is flushed with a large quantity of high pressure water and after being subject to full washing, slurry will flow into sieve-mesh plate and a fraction of 20 – 60 mm size of ore is fed into intermediate cell of the chute for processing.

Undersize product with a fraction of ≤20mm placer is distributed to the chutes at two sides of the lower layer with the chute bottom provided with lattice bar and felt mat. When slurry flows through the lattice bar and the felt mat, stratification is performed in density and grain size. Gold grain and heavy minerals are concentrated on the felt mat and the chute is provided with theftproof door lock. When a shift is changed for cleaning the felt, the lock will be opened by an assigned person. The concentrate cleaned out is transferred into the vibrating chute for cleaning and placer gold and other heavy minerals are separated out using table before being subject to chemical treatment for delivery to smelting furnace for production.