Low Crushing Rate Grinding Ball for Copper and Gold Ore Primary Ball Mills

Product Description

Product Description

B2 / B3 Forged Steel Grinding Balls for Copper and Gold Ore Primary Ball Mills - Ø50-100mm, Low Crushing Rate <1%, High Impact Toughness ≥12 J/cm²

JUNDA B2 / B3 Forged Steel Grinding Balls are designed for primary ball mill grinding of copper ore and gold ore, where the grinding media must withstand repeated impact, abrasive wear and continuous mill operation.

Available in Ø50-100 mm, these forged steel grinding balls are suitable for primary grinding circuits where larger grinding media are required to break down relatively coarse ore feed.

With controlled forging and heat treatment, JUNDA grinding balls provide high impact toughness, consistent hardness, low breakage and stable wear performance.

Product Attributes

Field	Value
Product Name	B2 / B3 Forged Steel Grinding Ball for Copper and Gold Ore Primary Ball Mill
Material	B2 (Cr 0.2-0.6%) | B3 (Cr 0.7-1.2%)
Size Range	Ø50 mm to Ø100 mm (primary grinding); Ø20-Ø50 mm available on request
Surface Hardness	B2: 62-65 HRC | B3: 60-63 HRC
Core Hardness	B2: 60-63 HRC | B3: 58-62 HRC
Impact Toughness	≥12 J/cm²
Crushing Rate	<1% (verified by 8m drop test, 20,000+ cycles)
Application	Copper Ore Primary Ball Mill, Gold Ore Primary Ball Mill
Processing Type	Forged (Air Hammer) + Quench & Temper
Standard	ISO 9001:2015, GB/T 17445
Packaging	1,000 kg Iron Drum / Ton Bag
Production Capacity	100,000 Tons/Year
Lead Time	14 Working Days (Standard)
MOQ	500 kg
HS Code	7326110000

Designed for Copper & Gold Ore Primary Ball Mills

Primary grinding is the first major grinding stage after crushing. The grinding media must generate sufficient impact force to reduce relatively coarse ore while maintaining acceptable wear and breakage performance.

JUNDA Ø50-100 mm B2 / B3 forged steel grinding balls are developed for this type of demanding grinding environment.

Typical Applications

• Copper ore primary ball mills
• Gold ore primary ball mills
• Copper-gold ore grinding
• Primary grinding circuits
• Closed-circuit ball mills
• Wet grinding of hard and abrasive ores

These grinding balls are particularly suitable where high impact resistance and low breakage are important for maintaining a stable grinding media charge.
 

4.  Product Overview - Why Primary Ball Mills Demand Specific Media

In copper and gold ore processing, the primary ball mill receives crushed ore (typically P80 10-25 mm) and grinds it to flotation or leach feed (P80 75-150 μm). This stage subjects grinding media to the highest combined impact-plus-abrasion loads in the entire circuit.
 

4.1  The Two Failure Modes at Primary Mill Scale

Breakage under impact: At Ø75-100 mm, ball kinetic energy at typical drop heights (1.5-3 m) reaches 150-400 J per impact event. A ball with internal voids or soft core fractures under repeated loading. Fragments at this size wedge into grate plates, accelerate liner wear, and cause immediate process disruption.

Abrasion wear: Copper and gold sulphide ores commonly have Bond Abrasion Index (Ai) of 0.2-0.8 g/rev. Without adequate surface hardness (HRC 60+), media wear rate rises sharply, increasing media consumption cost per tonne of ore processed.

Jinan Junda's B2 and B3 forged grinding balls address both: forged construction eliminates structural defects that cause breakage; controlled alloy content (Cr 0.2-1.2%) delivers HRC 60-65 surface hardness with ≤3 HRC core differential to maintain hardness through the full wear cycle.

 

Grade Selection - B2 vs. B3 for Primary Grinding

Property	B2	B3
Cr content	0.2-0.6%	0.7-1.2%
Si content	0.15-0.35%	1.2-2.0% (higher hardness ceiling)
Surface HRC	60-65	60-63
Core HRC	58-64	57-62
Impact toughness	≥12 J/cm²	≥12 J/cm²
Recommended Ai	≤0.4 g/rev	>0.4 g/rev
Recommended pH	6-9 (standard)	<6 or highly acidic circuits
Cost	Lower	Moderate premium (~10-15%)
Best application	Standard porphyry copper, gold CIL circuits	High-silica skarn, epithermal copper, abrasive ores

Note: Rule of thumb: Start with B2. Upgrade to B3 if ore Bond Ai >0.4 g/rev, silica content is high, or circuit pH runs below 6.

Grade

Main Characteristics

Typical Application

B2

High hardness, good wear resistance, balanced toughness

Copper & gold ore ball mills

B3

Higher toughness and impact resistance for demanding conditions

Larger or higher-impact primary grinding

The final grade should be selected according to ore abrasiveness, impact conditions, mill size, ball consumption and operating experience.

For general primary grinding conditions with moderate ore abrasiveness (Bond Ai ≤0.4 g/rev), B2 provides a suitable balance between hardness and wear resistance.

For demanding impact conditions, B3 can be considered where higher toughness is required.

Technical Parameters

B2 Grade - Primary Grinding (Ø50-100 mm)
Size	Inch	Weight (kg)	Tol. (mm)	Grade	Surface HRC	Core HRC	Application
Ø50	2"	0.600±0.050	±1.5	B2	62-65	61-64	Primary / transition
Ø60	2-1/2"	1.000±0.050	±1.5	B2	62-65	60-62	Primary grinding
Ø65	2-1/2"	1.300±0.050	±1.5	B2	61-64	60-62	Primary grinding
Ø75	3"	2.000±0.060	±2	B2	61-64	60-62	Primary grinding
Ø80	3"	2.100±0.060	±2	B2	61-63	59-62	Primary grinding
Ø90	3-1/2"	3.000±0.070	±2	B2	60-63	59-62	Primary grinding
Ø100	4"	4.100±0.150	±2	B2	60-63	58-61	Primary grinding

 

B3 Grade - High-Abrasion / Acidic Circuit (Ø65-100 mm)
Size	Inch	Weight (kg)	Tol. (mm)	Grade	Surface HRC	Core HRC	Application
Ø65	2-1/2"	1.300±0.050	±1.5	B3	61-63	60-62	Primary grinding
Ø75	3"	2.000±0.060	±2	B3	61-63	60-62	Primary grinding
Ø80	3"	2.100±0.060	±2	B3	60-63	59-62	Primary grinding
Ø90	3-1/2"	3.000±0.070	±2	B3	60-63	59-62	Primary grinding
Ø100	4"	4.100±0.150	±2	B3	60-63	57-60	Primary grinding

 

Chemical Composition
Grade	C%	Si%	Mn%	Cr%	P%	S%
B2	0.72-1.03	0.15-0.35	0.30-1.20	0.2-0.6	≤0.035	≤0.035
B3	0.53-0.88	1.20-2.00	0.50-1.20	0.7-1.2	≤0.035	≤0.035

High Impact Toughness ≥12 J/cm²

Primary grinding generates repeated impact between the grinding balls, ore and mill liners.

Impact toughness ≥12 J/cm² helps the grinding balls withstand repeated impact during continuous mill operation.

Higher impact resistance can help reduce the risk of premature cracking and breakage when the grinding media are properly matched to the mill operating conditions.

Low Breakage Rate <1%

Grinding media breakage can increase media consumption and disturb the grinding media size distribution.

JUNDA forged steel grinding balls are manufactured through controlled forging and heat treatment to achieve a dense internal structure and stable mechanical properties.

With a specified breakage / crushing rate below 1%, the grinding balls are designed to maintain stable performance in demanding primary grinding applications.

The actual breakage rate depends on ball size, grade, mill conditions, ore characteristics and operating parameters.
 

High Hardness and Wear Resistance

Copper and gold ores can be highly abrasive, making wear resistance an important factor in grinding media selection.

JUNDA B2 / B3 forged steel grinding balls are heat-treated to develop the required hardness and mechanical properties.

High hardness helps resist abrasive wear, while sufficient toughness helps the balls withstand repeated impact.

The objective is to achieve a balanced combination of:

Hardness + Toughness + Wear Resistance + Breakage Resistance

rather than maximizing hardness alone.

Consistent Hardness Distribution

Uniform and controlled hardness is important for stable grinding media wear.

JUNDA controls the forging and heat treatment processes to maintain consistent mechanical properties throughout the ball section.

A controlled hardness distribution helps:

• Reduce uneven wear
• Maintain a more stable ball size distribution
• Improve grinding consistency
• Reduce premature breakage
• Support predictable grinding media consumption

Application Scenarios

1.  Copper Ore Primary Ball Mill (Ø65-100 mm B2/B3)

After SAG mill or crushing, copper sulphide ore enters primary ball mills targeting flotation feed at P80 75-150 μm. High ball-to-liner and ball-to-ball impact energy in this stage demands structural integrity above all. B2 (Ø75-100 mm) delivers the optimal balance for standard porphyry copper circuits. B3 is recommended for high-silica skarn or epithermal copper ores with elevated Bond Ai.
 

2.  Gold Ore Primary Ball Mill (Ø50-90 mm B2)

Gold ore primary mills (CIL/CIP circuit feed preparation) typically use smaller primary ball charges (Ø50-90 mm) due to lower ore hardness (Bond BWi 10-18 kWh/t for most oxide and transitional gold ores). B2 grade provides sufficient hardness at lower alloy cost. Low iron dissolution of B2 also protects downstream cyanide leach circuit efficiency.
 

3.  Ball Size Selection Guide

Ore Type	Bond BWi	Bond Ai	Ball Size	Grade
Soft gold oxide	8-12 kWh/t	<0.1 g/rev	Ø50-65 mm	B2
Medium gold sulphide	12-16 kWh/t	0.1-0.3 g/rev	Ø65-80 mm	B2
Hard porphyry copper	14-18 kWh/t	0.3-0.5 g/rev	Ø75-100 mm	B2
Hard abrasive copper / skarn	16-22 kWh/t	>0.5 g/rev	Ø80-100 mm	B3

Note: For SAG Mill applications requiring Ø100-150 mm, see our dedicated SAG Mill product page (B3 / 42CrMo). For copper concentrate regrinding (Ø20-50 mm), see our Copper Regrind page.

 

Company Profile

COMPANY INTRODUCTION

Jinan Junda Industrial Technology Co., Ltd. specializes in the manufacture and export of forged steel grinding balls, backed by advanced equipment and rigorously controlled production processes. Our forged steel balls deliver high hardness, excellent wear resistance, superior impact toughness and consistent roundness throughout their service life - with a breakage rate of less than 1%.

Our grinding balls are widely used in ball mills across gold mining, copper mining, iron ore processing, cement production, thermal power generation, chemical processing and other industries. To ensure reliable and consistent product performance, we have built a comprehensive quality management system supported by advanced testing equipment, including OES spectrometry, full-section hardness analysis and drop-ball impact testing.

Certifications

FAQ

Q1: What's the delivery time?

A : The standard lead time is approximately 14 working days, depending on order quantity and production schedule.
 
Q2: What's package?
A: 1,000 kg Iron Drum / Ton Bag
 
Q3: Do you provide technical support?
A: We have a professional technical support team to provide timely assistance. We can also prepare technical documents according to your requirements. You can contact us by phone, online chat, WhatsApp or Skype.
 
Q4: What's the payment method?
A: T/T, Western Union, MoneyGram, L/C

Q5: How do you ensure the products arrive safely?
The grinding balls are securely packed in iron drums or ton bags for international transportation. We also inspect the products and packaging before shipment to ensure they meet the agreed specifications.