Code for Design of Ferroalloy Process and Equipment English
1 General Provisions
1.0.1 This code is drawn up for the sake of execution of ferroalloy engineering construction as advanced technology, economical and reasonable, safe and suitable, energy saving and environmental protection.
1.0.2 This code is suitable for ferroalloy process and equipment engineering design in new project, modification project and expansion project.
1.0.3 Besides this code, the ferroalloy process and equipment engineering design shall be also in accordance with stipulations of relevant national standards currently in force.
2 Terms
2.0.1
submerged arc furnace
submerged arc furnace (hereinafter referred to as SAF), also called resistance furnace, is a type of furnace which is used to produce ferroalloy by smelting ore through reduction method using carbon reducing agent through the utilization of arc heat and resistance heat of material, and its operation is continuous.
2.0.2
electrode slipping
during smelting process, the electrode will be slipped downward with certain length at regular time intervals or according to furnace conditions considering electrode loss so as to maintain operation of electrode working end length.
2.0.3
electrode hoisting
electrode will be entirely hoisted through electrode brake.
2.0.4
self-baked electrode
the lumpy electrode paste will be baked into an entirety locally inside electrode shell utilizing the resistance heat generated by electric current.
2.0.5
metallothermics
metallothermics refers to a kind of technological process for producing ferroalloy by utilizing heat generated through chemical reaction in which metal with higher chemical activity is used for reduction of another type of oxide.
2.0.6
shaking ladle process
this process is used for producing low carbon and medium carbon ferromanganese (Fe-Mn)and some other alloys.The ore, flux and liquid alloy which are preheated are charged into shaking ladle for shaking, and the charge will be molten by utilizing the sensible heat and latent heat of the charge to produce alloy through reduction reaction.
3 Process and Equipment of Pyrometallurgy
3.1 General Requirements
3.1.1 Ferroalloy SAF shall be oriented at large scale, closed type and computer control.
3.1.2 The equipment and auxiliary facilities and utility system selected for each process of the workshop shall be complete, and the technological process shall be smooth.
3.1.3 Smelting workshop newly designed shall feature improved mechanization and automation level and improved working conditions.
3.1.4 Practical, safe and energy-saving mechanical equipment shall be selected to be easy to operate.
3.1.5 Auxiliary facilities shall be equipped in unified form.
3.1.6 Pressure test shall be done before installation of hydraulic cylinders for electrode regulating, slipping and electrode holder and the hydraulic cylinders of the same type with similar no-load action pressure shall be grouped to be installed on the same electrode.The vertical tolerance shall not exceed 0.50mm/m.
3.1.7 While jointing two sections of electrode shells, the top and bottom of fins shall be aligned and connected.The vertical tolerance of electrode shell from the end face of upper clamping brake shall not exceed 2‰ of the length of this electrode shell section.While continuous welding is adopted, the weld seam at external surface shall be ground smooth after welding.
3.1.8 While installing fume hood or furnace roof, its center shall be coincident to the center of SAF, and the tolerance of coaxiality shall not exceed 5mm.
3.1.9 Insulation inspection shall be carried out after completion of fume hood or furnace roof installation, and other individual components shall be inspected one by one.The insulation resistance shall not be lower than 1.50MΩ, and the total insulation resistance of entire assembly shall not be lower than 0.15MΩ.There shall be no arc striking while detecting the ground insulation of 3 phase electrode by using electric welding machine.
3.1.10 Pressure test is to be carried out after compressed air system installation is completed.The test pressure shall be 1.25 times of the working pressure during normal working, and there shall be no leaking for successively 30minutes.
3.1.11 The cooling water system shall be in accordance with the following requirements：
1 It shall meet cooling requirements of each cooling position of SAF.
2 Water supply pressure shall be maintained at 0.3MPa-0.5MPa, and the water supply header shall be equipped with temperature and pressure detection device.
3 Return water branch pipes may be equipped with temperature and flow detection, and marking shall be made at return water flume of each return water pipe.
4 Joint of each cooling water supply pipe shall be equipped with compressed air connector.
5 Length of hose shall meet requirements of max.stroke of electrode.
6 After pipeline installation is completed, it shall be flushed and shall be subject to hydrostatic test.
3.1.12 The busbar, holder and tube leading into fume hood shall be cooled with softened water.
3.1.13 For cooling of transformer, a separate cooling system shall be foreseen.
3.1.14 The circulation rate of cooling water shall not be lower than 95%.
3.1.15 Forced cooling method shall be adopted for bottom.
3.1.16 Fume waste heat and gas shall be recovered.
3.1.17 Fume produced from SAF shall be cleaned by bag filter.
3.1.18 Casting workshop must be equipped with foundry crane.
3.1.19 Welding method shall be adopted for connection between burn-through buses, and the surface shall be free from dirt and metal oxide.
3.1.20 The equipment with storage time exceeding one year shall be dismantled, cleaned and oiled before installation.The rusting pipes and weldment shall be subject to derusting and painting.
3.1.21 Hydraulic media shall be kept clean, and it shall be filtered at least once per month, and replaced once per year.The media temperature shall be controlled within the range of -20℃-+60℃.
3.2 Process
3.2.1 The workshop composition of SAF and refining furnace shall be in accordance with the following requirements：
1 The production system of SAF workshop shall consists of proportioning station, smelting workshop (including transformer room and control room), casting workshop, finishing workshop and slag treatment system.
2 The production system of refining furnace workshop shall consists of proportioning workshop, smelting workshop (including transformer room and control room), casting workshop and finishing and crushing workshop.
